MPs were turned away from the House of Commons chamber on Monday afternoon as water was pouring in through the ceiling because of a leak.
Business in the house was scheduled to start at 2.30pm with prayers followed by work and pensions questions.
But the leak caused the beginning of the sitting to be delayed by just over one hour.
Staff had tried to keep the chamber dry by draping protective coverings over the central table, while numerous buckets near the green benches caught rain drops from above.
Police officers were also seen entering the Commons chamber with what appeared to be water-absorbent blankets.
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Commons Speaker Sir Lindsay Hoyle said an air-conditioning unit from a nearby office was to blame for the leak.
Conservative MP Flick Drummond said: “We have got DWP questions, which are really important. So it is a bit irritating to have that starting late. And it pushes everything else back too, so we might have a very late night tonight.” Asked if the incident made her concerned, she replied: “Yes, I have done the basement tour. This is a very dangerous place to be. “I can tell you, we need to do some restoration very quickly on this and perhaps I think the only way we are going to do that is to move out now because it’s going to be too expensive. “But yes, we have water leaks, we have things falling down from ceilings and downstairs, the electricity cables and gas and water leaks.”
Garry Graham, deputy general secretary of Prospect union, said Monday's leak shows the need for urgent restoration and renewal work around Parliament. “The parliamentary estate needs to be fixed up so that it can remain a functioning and safe place to work for the foreseeable future," he said. “The cheapest, safest solution with the shortest timescale attached is a full decant yet ministers have decided that this would be too much disruption. “If one leak can cause this much disruption it doesn’t take a genius to work out that decades of operating with Parliament as a building site will cause untold problems.”
There have been repeated delays to plans to restore the crumbling Palace of Westminster amid safety concerns about the Victorian building's crumbling masonry and the lack of protection against flooding.
The issue was brought into focus on April 4 2019, when the House of Commons had to be suspended for a day after water began pouring into the chamber from the ceiling, soaking a section of the press gallery.
This occurred during a debate on tax matters and while proceedings carried on for a few minutes, the noise of water pouring into the press gallery soon became overwhelming.
The restoration of Parliament will cost billions of pounds. Earlier this year, a report showed that restoring the Palace of Westminster without finding a new home for MPs could take up to 76 years, with a repairs bill reaching £22 billion.
The project's sponsor body and delivery authority said the cheapest option would involve a "full decant" of the palace for between 12 and 20 years, with the work costing in the region of £7 billion to £13 billion.
In this scenario, with MPs elsewhere for much of the time, the report estimated the restoration would take between 19 and 28 years.