Parliamentary authorities have warned MPs about the risk of “falling masonry” outside the House of Commons, HuffPost UK can reveal.
Officials have had to introduce “exclusion zones” and a police officer is keeping watch along the north side of the historic Westminster Hall.
The safety measures have been brought in after staff found stonework was “degrading at a faster rate than expected”.
The hall is the oldest building on today’s parliamentary estate and has been the scene of historic events, including the state trials of William Wallace, Sir Thomas More, Guy Fawkes and Charles I.
Many notable occasions of lying-in-state have also taken place in the hall including William Gladstone, King George V, Winston Churchill and the Queen Mother.
But in a damning indictment of the condition of the building’s exterior, measures have had to be brought in to protect staff walking by from “falling masonry”.
An email to MPs, seen by HuffPost UK, said: “Following a survey of the north facade of Westminster Hall, the area has been identified as degrading at a faster rate than expected with a risk of stone fall identified. Additional safety measures have been put in place.
“Following tactile inspections, mitigation is required to protect the immediate area below from falling masonry. Temporary exclusion zones have been formed using a flexible barrier system to the East and West of the main entrance.”
The email was sent to MPs yesterday, the day before the biggest event in the parliamentary calendar - the State Opening of Parliament in which Prince Charles delivered the Queen’s Speech.
They said the measures would remain in place until “protective scaffolding” is installed, due at the start of the summer recess or “earlier if possible”.
MPs were then warned to take “particular care” in the area and avoid the cordoned off areas.
Figures released earlier this year revealed there had been 15 incidents in the last three years in which stonework had come crashing down.
In April 2018, a football sized chunk of masonry broke away from a stone angel on parliament’s Victoria Tower and plummeted 230ft to the ground. And in October 2017 an MP’s car windscreen was smashed when a piece of masonry fell from a building.
Despite being one of the world’s most iconic heritage sites, the palace is in a state of disrepair and urgently needs major restoration works.
A recent report found the works needed to save the palace could cost up to £22 billion and last 76 years.
But the project has been subject to a number of set backs and a desire from some MPs to remain in the historic building.
It comes after HuffPost UK revealed that renovation work had to be halted and the Health and Safety Executive launched an investigation after a asbestos leak last October.
Up to 117 people were potentially exposed to asbestos in the leak over four days during works on the Speaker’s bedrooms.
A UK parliament spokesperson said on Tuesday: “Following a survey of the north facade of Westminster Hall, a risk of stone fall has been identified.
“As a result, additional safety mitigations are being implemented whilst investigations continue and conservation takes place.
“We work hard to keep parliament safe for both the members of the public that visit and for the staff and parliamentarians that work here. Where issues are identified we act quickly to address them.”