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IMAGINATIVE photographic techniques developed by a surveying technology company are playing a key role in a major restoration project about to begin at one of Britain’s most important historical monuments.

Survey Inspection Systems (SiS) Limited, based in Spennymoor, County Durham, is providing English Heritage with highly detailed video images from inside chimney flues and other shafts at Dover Castle, in Kent - a site most famous for its labyrinth of secret tunnels that stretch out under the English Channel.

The photographic survey is part of a wider £5m investment programme by English Heritage at the castle to enhance the visitor experience and help reverse falling visitor numbers.

SiS, one of the UK’s leading providers of a range of advanced surveying and data collection techniques, is best known for its work on behalf of Network Rail and the London Underground.

But director Phil Burgess says the company is fast becoming recognised for developing bespoke solutions to access and photograph the unreachable.

In this case a camera casing was developed to carry a video camera with fish eye lens, which bizarrely, resembles a chimney brush. The “bristles” hold the camera’s position a fixed distance from the walls, while electronic controls enabled the camera to be rotated 360 degrees to provide an inch-by-inch video map.

The video footage obtained at Dover Castle is helping English Heritage determine the age of fireplaces and chimneys, while also assessing their condition. It is also enabling researchers to establish historical accuracy as the attempt to meticulously present the internal appearance of the keep is as it would have looked during Henry II’s reign in the 12th Century.

But English Heritage’s Senior Properties Historian Paul Pattison, who is leading the research project, said that SiS’s video survey had led to several dramatic discoveries.

“Thanks to SiS’s survey work, we have identified two fireplaces we didn’t know about and one ‘chimney shaft’ that leads down from the roof, but not to a known fireplace,” said Mr Pattison.

“The keep at Dover Castle was the last of the great tower keeps to be built in Britain, between 1181 and 1189, and is one of the largest and most elaborate ever built. It is an extraordinary building.

“The chimney shafts at Dover Castle are roughly 18in by 18in, but not all shafts are straightforwardly vertical, lighting was also a major challenge, but the results so far are very detailed.

“We hope SiS’s video map may also help to explain a rainwater run-off system from the roof of the keep which runs not only into the guardrobe, or toilet shaft, but also feeds lead pipes carrying the fresh water supply, which is unusual and would have been a great asset during a siege situation.”

SiS was recommended for the Dover project by Paul Bryan, Head of English Heritage’s Metric Survey and Photogrammetry Team, after they used a hot-air balloon to obtain detailed photography of the upper parts and tops of walls at Fountains Abbey, in North Yorkshire, to help English Heritage assess the extent of weather damage without the need for scaffolding or cherry-pickers.

Mr Bryan said: “Conventional means of access, such as ladders or scaffolding, often provide only a limited view, you are continually having to move them around, and there are related health and safety issues, while hydraulic lifts can damage the ground which itself could be of heritage value. So remote systems, such as balloons and micro helicopters, while weather-dependant, offer innovative alternative means of accessing high level, difficult to reach and vulnerable areas.”

“In both cases, SiS was set a difficult task and we have been suitably impressed
by the way they adapted their technology to meet the challenge.”

SiS has a ten-year association with Britain’s rail and waterways, and civil engineering and building sectors, primarily providing topographical surveys, aerial laser mapping and engineering surveys, but Mr Burgess says its work for English Heritage is an example of the wide-ranging applications it is now pursuing.

Mr Burgess said: “The accuracy, clarity and reliability of the information we gather is of paramount importance, as is the speed at which it is obtained, but alongside these core values we take enormous pride in coming up with survey solutions that overcome even the most challenging environment or location.

“We like to think that what sets SiS aside is our willingness to go the extra mile.”

For further information contact Phil Burgess at SiS on 01388 810308.

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