Hidden section of medieval river wall discovered under Palace of Westminster during deep borehole investigations

Over the summer and early autumn, specialists spent 4850 hours examining 160 rooms and drilling boreholes up to 70 metres deep to assess ground conditions around the Palace of Westminster. The surveys are helping restoration teams develop the most detailed ever record of the Palace of Westminster to inform decisions about essential restoration work.

During a geotechnical borehole investigation in Chancellor’s Court, near the House of Lords chamber, the discovery of a section of possible medieval river wall meant the borehole drill was paused and the discovery assessed by archaeologists from the Museum of London Archaeology (MOLA).

The structure is likely to be at least 700 years old and is made from Kentish Ragstone, a hard grey limestone quarried from Kent that was also used in the construction of the Tower of London and Westminster Abbey.

Borehole drills gathered dozens of ground samples from under the Palace which will be sent to a specialist lab in Coventry for testing to better understand the composition of the ground. MOLA will also conduct its own archaeological report based on the data from the boreholes to confirm more about the discovery of the possible river wall.

Lord Speaker, Lord McFall of Alcluith said:

“The Houses of Parliament are full of extraordinary history that is worth protecting for future generations, as this discovery demonstrates. A new approach to delivering the works that commands the support of both Houses, as well as a change in governance, means we can be more nimble and get on with the essential jobs like conservation of the building fabric without delay.” 

Sir Lindsay Hoyle, Speaker of the House of Commons said:

“The Palace of Westminster is a treasure trove of history, and making sure this is properly conserved whilst also getting on with the vital job of restoring this unique place is a key priority. I’m delighted that under the new approach to delivering the restoration and renewal works agreed by Members, we can ensure that essential jobs can get under way as soon as possible.”

David Goldstone, CEO of the Houses of Parliament Restoration and Renewal Delivery Authority, said:

“We’re getting on with the job of protecting the Palace of Westminster, carrying out thousands of hours of surveys to understand the condition of the building. This is a national effort, calling on businesses and expertise from across the nation. 

“Small to medium sized companies are already benefiting from Restoration and Renewal Delivery Authority surveying work, with five out of our seven recent contracts awarded to small to medium sized enterprises.”

Patsy Richards, interim CEO, Houses of Parliament Restoration and Renewal Sponsor Body said: “We expect more exciting finds from dozens of surveys carried out over the coming months. We are also working really closely with the teams who keep the Palace running now. As we learn more from our surveys, we can develop in more detail proposals to agree a safe and cost effective way to plan the work needed to restore the Palace of Westminster and preserve it for future generations.”

The boreholes are part of an extensive programme of sensitive building investigations by the Houses of Parliament Restoration and Renewal Delivery Authority. Archaeologists have been on-site for each of the boreholes to record any finds of historical significance which could add to our records of the Palace. A small amount of material from the river wall was removed for analysis before the site was carefully sealed up again to protect the structure.

The discovery is likely the second finding of a part of the medieval river wall which runs under Parliament, which was first identified in Black Rod’s Garden in 2015, when medieval timber structures thought to represent waterfront revetments were discovered. The wall runs alongside the medieval location of the riverside. When the Palace was built in the 1800s, after many of the medieval buildings burned down, land was reclaimed from the Thames to make the Palace site bigger.

Elsewhere, 160 rooms across Parliament were inspected by surveyors who are lifting up floorboards, sensitively drilling into walls and removing ceiling panels to look at a range of issues such as wall cavities, the material makeup of the building and the weight-bearing of historic flooring. Specialist teams will continue to inspect the hundreds of miles of interconnected power cables, gas, water and heating pipes as well as outdated water and sewerage systems.

Since January, Restoration and Renewal Programme teams have examined over 2,089 spaces across the Palace of Westminster. Other surveys conducted earlier in 2022 include a thermographic study of heat loss from the building, examination of room spaces, and studying conditions just under the surface of the ground to measure tree roots and other obstructions which could impair restoration works.

In July both Houses of Parliament approved a new approach for how the work to restore and renew the Palace of Westminster should be governed and delivered. As a result, Parliament agreed the programme of works should initially focus on the following priority areas:

  • Fire safety and protection
  • Replacement of mechanical, electrical, drainage and plumbing, and data and communications systems
  • Asbestos management and wider health and safety issues
  • Conservation of the building fabric including stonework.

The Restoration and Renewal Programme will develop options, guided by the R&R Delivery Authority, which will include a variety of ways in which the works can be delivered, including minimising the time and extent to which Members and staff are asked to move out of the Palace and different levels of ambition for the works.