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Borehole deeper than Channel Tunnel dug under Parliament over Easter recess

Borehole deeper than Channel Tunnel dug under Parliament over Easter recess

Over the Easter Recess period the Houses of Parliament Restoration and Renewal Delivery Authority drilled an 84m borehole, deeper than the Channel Tunnel, as part of over 1500 hours of intrusive surveys across the Palace of Westminster.
Graphic depicting the depth of borehole drilling.


The borehole, the deepest to date by the Restoration and Renewal Programme, was dug to investigate the geological condition of the ground on which the Palace stands. It will help surveyors for the Delivery Authority confirm the different ground conditions under the Palace. At 84m deep, this borehole is deeper than the Channel Tunnel.

The Palace of Westminster needs extensive restoration work to continue to serve as the home of our democracy for generations to come. In March a Strategic Case report endorsed by the R&R Client Board – made up of the Commissions of both Houses of Parliament – was published. It sets out the three options identified to be taken forward for further work over the next year and which will be brought back to support decisions by MPs and peers on costed proposals in 2025.

Nigel Evans MP, Deputy Speaker of the House of Commons and Chair of the R&R Programme Board, said:


“We’re getting on with critical repairs and maintenance work across Parliament alongside important building surveys like huge underground boreholes as part of the extensive restoration and renewal of the Palace of Westminster.”

The Restoration and Renewal Programme is carrying out the tens of thousands of hours of complex building surveys and investigations needed to inform future decisions on the restoration work.

Matt White, Restoration and Renewal Programme Director said:


“Designing for a building as old and complex as the Palace isn’t easy, and we don’t always have complete plans we can work from due to the age of the building. To restore the Palace, we first need to understand it. These intrusive surveys help us better understand the condition of the Palace by looking at ground conditions, floors and ceilings, heritage items, and air quality. This information is used to inform the development of detailed architectural designs on every aspect of the Palace.”

Alongside the borehole, the Delivery Authority also conducted several other intrusive and non-intrusive surveys.

Primary services distribution


Risers and other spaces that contain pipes and wiring at 32 locations across the Palace were inspected as part of an ongoing primary services distribution survey which is checking vertical distribution routes for services. This information will inform designs for future services.

Air pressure leakage


A survey to measure the energy efficiency of rooms in the Palace was conducted with air pressure checks conducted in a low heritage-rated location to identify points of air leakage and heat loss. These checks follow a visit to the same location over the Christmas recess and enable a direct comparison between results obtained with and without seals around windows and vents.

Alongside these intrusive surveys, Heritage Project Officers from the Delivery Authority continued the non-intrusive Heritage Audit of the Heritage Collections within the Palace. Over 1000 hours have so far been devoted to auditing and cataloguing over 8,000 items. Parliament's collection of 11,000 works of art and items of historic furniture, clocks, ceramics and silver are of international significance. Much of the collection was designed by Augustus Pugin, who created the original interior of the building, and Giles Gilbert Scott, who was asked to rebuild and furnish the bombed areas of the House of Commons after the Second World War.

The Restoration and Renewal Programme, working collaboratively with the collection custodians in the two Houses of Parliament, will co-ordinate the removal of all these cultural treasures to ensure they are kept safe during restoration work on the Palace.