Gleaston Castle

This post was written by Louise Martin, Cultural Heritage Officer for Morecambe Bay Partnership

Gleaston Castle is a gem of a site; a little known and poorly understood courtyard or enclosure castle, located in the beautiful Furness Peninsula. The history of the site is scant and whilst it has been the subject of antiquarian and more recent documentary research, its origins and reason for construction still remain unclear. Some writers have proposed that the castle was constructed in the early 14th century as a response to the Scottish raids, although the site is not mentioned in documentary sources until some 30 years after these raids and may simply be a reflection of the wealth and status of the Lord of the Manor.

Today the site survives as the ruins of three towers with an associated curtain wall. As a Grade I listed building and Scheduled Monument this unique site is protected from development or destruction, however, this site is currently on the Heritage at Risk register with many conservation concerns.

Its crumbling stature is not new, the site is believed to have been dismantled after it ceased to be a manorial residence. It was described as a ruin in the mid-16th century and is depicted as such in engravings from the early 18th century.

Engraving of Gleaston Castle by Samuel and Nathanial Buck, 1727 showing the site in a ruinous state
Engraving of Gleaston Castle by Samuel and Nathaniel Buck, 1727 showing the site in a ruinous state

Whilst the site was subject to antiquarian attention, with plans and descriptions produced in the early 19th century, I was surprised to discover that the site had never been fully recorded, in particular the elevations of the structures which survive from its original layout.

To bridge this gap in the archaeological record and gain a better understanding of the site, Morecambe Bay Partnership applied to the Castle Studies Trust for a grant in late 2014. I was thrilled and delighted to hear the news that our application had been accepted and a generous £5,000 grant had been awarded to enable an aerial photographic survey and 3D model of the site to be produced. In addition, the grant would fund the production of a conservation assessment, outlining the historical background and current issues for the site.

Greenlane Archaeology Ltd. was commissioned to run the project, bringing in professional archaeological photographer Adam Stanford from Aerial-Cam to undertake the survey work. During the summer of 2015 Adam flew over the site with Remotely Piloted Aircraft (RPA)-a DJI Inspire 1 quadracopter fitted with an X3 gimballed camera producing still images at 12 megapixels. Professional photographers, such as Adam, have to follow strict guidance and regulations as part of their licence to undertake such work.

Many precautions had to be put in place before the RPA survey was undertaken by Adam a CAA licenced pilot
Many precautions had to be put in place before the RPA survey was undertaken by Adam a CAA licenced pilot
Adam from Aerial-Cam operating the quadracopter RPA
Adam from Aerial-Cam operating the quadracopter RPA

The photographic record from the air was supplemented by high-resolution (24 megapixel) images captured with a high-level telescopic pole and more traditional ground-based photography to obtain close up images of the structure.

Over 600 overlapping photographic images were taken to capture a detailed record of the site. Back in the office Adam used Agisoft Photoscan to process the data collected. The results were stunning, including aerial images and the creation of a 3D model, which enables the site to be ‘explored’ from the safety and comfort of a PC or tablet through Sketchfab.

Adam capturing some of the elevated images that would be used alongside the RPA images to produce an accurate and detailed 3D record of the site
Adam capturing some of the elevated images that would be used alongside the RPA images to produce an accurate and detailed 3D record of the site

 

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One of the most important outcomes of this project was the detailed orthophotos that were captured of the elevations of the castle’s ruins. We have been using these images to inspect the construction and conservation issues for the site, but primarily they form a permanent record of the castle that was lacking until this survey in 2015.

The aerial image and subsequent grey scale shading was particularly informative revealing furrows and a possible track way to the north-east of the castle. The track appears to lead to the north-western tower, the largest structure at the site and probably once the manorial residence. Within the curtain walls, areas of terracing and possible building platforms could be identified – but what could they be?

Aerial view of the site © Aerial-cam
Aerial view of the site © Aerial-cam
Shaded aerial view of the side which highlighted ridge and furrow and possible track way to the north-east of the castle, in addition to terracing and possible building platforms within the castle’s courtyard. © Aerial-cam
Shaded aerial view of the side which highlighted ridge and furrow and possible track way to the north-east of the castle, in addition to terracing and possible building platforms within the castle’s courtyard. © Aerial-cam

Supplementing the photographic work Greenlane Archaeology also undertook a topographic survey of the site to complement and enhance the results obtained.

Dan Ellsworth from Greenlane Archaeology undertaking the topographic survey of the south-east tower
Daniel Elsworth from Greenlane Archaeology undertaking the topographic survey of the south-east tower

In August 2015 we were delighted to host some of the trustee’s from the Castle Studies Trust (CST) along with supporters of the CST charity, who travelled to the Furness Peninsula to see the survey work in action. We were joined by the Historic England Heritage at Risk Officer, the Lead Archaeologist from Cumbria County Council, and Helen Evans who had compiled the Conservation Statement. Adam from Aerial-Cam gave a detailed demonstration on how the RPA captures the photographic images and how these are enhanced and combined to form the incredible 3D records of the site.

Adam from Aerial-cam demonstrating to Trustee’s and supporters of the Castle Studies Trust how the RPA captures the images from the air
Adam from Aerial-cam demonstrating to Trustee’s and supporters of the Castle Studies Trust how the RPA captures the images from the air

To put the site of Gleaston into context, the visitors were also taken on a tour of Piel Castle, which can be seen from the elevated position of the north-west tower at Gleaston. Piel Castle is positioned on a tidal island and we had to use the local ferry service to reach the site.

Boarding the ferry to Piel Island and castle
Boarding the ferry to Piel Island and castle

It was some months later, during discussions with Dr Richard Peterson and Dr James Morris of University of Central Lancashire (UCLan) Archaeology and Anthropology Department that the next piece of fieldwork was being determined. Each year UCLan host a field school for their first year archaeology students and the team were looking for a site to use to teach the concepts and theories of geophysical survey and laser scanning. We had some interesting research questions to answer, which had been formulated following the photographic survey – do any buildings survive within the courtyard formed by curtain wall and what are the features shown to the north of the castle? Together we thought that Gleason was the ideal site for this year’s field school.

Before any plans to be laid out we had to get permission from the landowners to allow this work to go ahead. Once this had been secured, we had to apply to Historic England for a Section 42 licence, as the site is Scheduled and such work is strictly monitored by Historic England inspectors.

Permission was granted for the work and the fieldwork was scheduled for the end of April 2016. In addition to UCLan students, the survey training was opened up to the community, with fifteen places available per day through the Heritage Lottery Funded Headlands to Headspace (H2H) Landscape Partnership Scheme, which I am currently running part of for Morecambe Bay Partnership.

On 25th April we started the work at the site, using earth resistance and magnetometry to survey areas within the curtain wall and to the north of the castle, where we had identified ridge and furrow and the track way. The training attracted participants from as far afield as Liverpool and Carlisle as well as some local residents to Gleaston Village. The north-west tower was also subject to detailed laser scanning, which will supplement the photographic record produced by Aerial-Cam. The weather was, well, challenging especially for the end of April with heavy downpours and even snow hampering our progress on site!

H2H Volunteers undertaking an earth resistance survey at the site
H2H volunteers undertaking an earth resistance survey at the site
One of the first year students from UCLan undertaking a magnetometry survey. Still smiling despite the cold!
One of the first year students from UCLan undertaking a magnetometry survey. Still smiling despite the cold!

The team of students, together with volunteers and the fabulous UCLan staff persevered and we completed a significant amount of survey across the site. The results of the survey work are currently being processed by the team at UCLan, however, initial interpretation of the data is highlighting garden features to the north of the site and possible post-built structures to the south-west of the courtyard.

Interpreted results of geophysical survey at Gleaston Castle by Richard Peterson of UCLan. Base mapping contains OS data © Crown Copyright and Database right 2015. An EDINA/Digimap supplied service.
Interpreted results of geophysical survey at Gleaston Castle by Richard Peterson of UCLan. Base mapping contains OS data © Crown Copyright and Database right 2015. An EDINA/Digimap supplied service.

All this recent work is enabling professionals to gain a better understanding of the site. For the first time we have an accurate photographic record of all the standing remains and have started investigating what below-ground remains may survive beneath the soil.

Morecambe Bay Partnership would like to thank the Castle Studies Trust and all their supporters for enabling the survey work to take place and highlight the importance of this site and the conservation issues the site currently faces.

We would also like to thank the landowners who have provided us with special permission to undertake this survey work and the team from Historic England and Cumbria County Councils Lead Archaeological Advisor who have provided advice and guidance along the way.

It is hoped that the work undertaken so far will be built on in future years with additional survey and assessment, finding positive solutions to protect this rare and fascinating site.

Small Unmanned Aircraft and archaeology – why now?

In 2015 the Castle Studies Trust and the Morecambe Bay Partnership worked together to record the remains of Gleaston Castle in Cumbria. By using an unmanned drone to photograph the castle we were able to reach every part of the building. Below is an excellent explanation from Museum of London Archaeology’s Dr. Peter Rauxloh of how this technique works. It was originally published on MOLA’s blog.

Archaeologists have known about the benefits of investigating archaeology from an aerial perspective for more than 150 years, arguably longer, but the day-to-day use of aerial survey in MOLA’s work has been hampered by cost.

The model drone was a very popular Christmas present last year; a clear indication that cheap aerial photography has arrived. The big innovation from the perspective of archaeological aerial survey is the arrival of affordable digital photogrammetric software and automated flight control.

Photogrammetry is the practice of taking measurements from images. It is based on the fact that the position of an unknown point in 3D can be calculated if it is viewed from at least two other known points. This is the principle of triangulation, as important to map makers in the 17th century, as it is today.

The software in question uses the principle of photogrammetry and applies it to the processing of digital images to create 2D orthomosaics and 3D models. In essence, the traditional technique of aerial photogrammetry used a small number of high quality images taken with expensive specialist cameras from real aircraft, on which a small number of common points were identified between adjacent images. The new method uses a large number of images, taken with a standard consumer grade digital camera from cheap aerial platforms and is able to identify thousands of common points between images. Thus the technique tightly locks together overlapping areas to create robust orthogonal mosaic and highly detailed 3D models.

The amount of overlap required between images in order to create robust models is very high, typically 75-85% between each successive image. This means that 85% of one image must still be visible in the next image, but how does one ensure that critical degree of overlap is maintained?

Typically an aerial survey will be flown in a grid, much like a tractor ploughing a field, and each successive image needs 75-85% overl ap with its predecessor. Moreover once it has turned and starts to fly back over the site, it must also get 60-70% overlap between the images on each leg. For small survey areas the aircraft is flown manually since it is easy to ensure the area is well covered with images,  but it is far more difficult to maintain the required consistency on a large site.  This is why MOLA use an autopilot and have it follow a flight plan.

A flight plan is a group of 3D coordinates or waypoints between which the aircraft navigates using its on-board GPS. To position these waypoints so the images overlap a number of variables need to be balanced. These include the camera’s field of view, frequency of image capture and the desired flight height and the speed of the aircraft. These in turn need to be considered against the size of the area to be flown and how long the aircraft can safely stay in the air.

Below you can fly round the model of Gleaston Castle.

Gleaston Castle
by aerial-cam
on Sketchfab

Bringing Pleshey Castle’s history to the public

Betrayal, intrigue, fire, a king arresting one of his men, and the richest man in England. In 850 years Pleshey Castle has seen it all.

The village and castle owe their existence to Geoffrey de Mandeville who founded both in the 12th century. At the height of his power he was the richest man in England apart from the king, but lost it all when he was accused of being a traitor. Pleshey was owned by his descendants (though in the hands of the king) before it passed to the Bohun family by marriage. It remained with them until 1380 and in 1419 Pleshey Castle became part of the Duchy of Lancaster. Because of the Duchy’s ownership we have detailed accounts of building work in the 15th century. By 1559 the castle stood empty, and now survives as some very impressive earthworks.

Throughout its history the castle was remodelled several times – sometimes to improve the accommodation, at least once to repair fire damage, and once because it had been partly demolished. Excavations between 1972 and 1981 led by S.R. Bassett tried to shed light on this complicated history. Unfortunately this important work never saw the light of day. Notebooks and context sheets were left in the archives, out of reach of all but the most determined until now.

Our tour group in the outer bailey
Our tour group in the outer bailey

Patrick Allen and Nick Wickenden are leading the efforts to get the results of the excavation published. The Castle Studies Trust have funded the creation of detailed drawings showing the work. They provide an invaluable visual reference, and show how parts of the castle have developed.

Earlier this month we visited the castle with some of our donors. As well as exploring the castle it was a chance for donors to talk to trustees and see first-hand how valuable the charity’s work is.

Crossing the moat surrounding the castle you get an idea of how impressive the site is. The motte at the heart of Pleshey is an impressive 17m tall while the ramparts are nearly 5m high and cut you off from the outside world. You can still see where the chapel was excavated and a section was cut through the rampart.

Pleshey is privately owned so if you want to visit you have to arrange it in advance. This is typically of the sites we work with, and we give donors the opportunity to look round. Patrick and Nick gave us a tour, explaining the colourful history of the site and what they were doing to publish the excavations. Behind the scenes, the illustrations complemented the research and helped understand the phasing of the site.

It can take years for excavations to be fully processed and reach the stage where the results are ready for the general public. Sometimes that stage is never reached making it much more difficult for people to access information. Because of your donations we’re bridging the gap.

We’re looking forward to seeing the final results!

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