MPs, peers and staffers were evacuated from the UK Houses of Parliament in reaction to a suspected fire alarm on Monday 10 July. House of Commons sources said the incident happened around 10:45 BST.

But the London Fire Brigade was not called to the Westminster landmark. "We can confirm that we have not been called to a fire alarm sounding at the Houses of Parliament," a spokesperson said.

The cause of the alert has not yet been made public, but parliamentary passholders, including reporters and MPs, were allowed back into the estate around 10 minutes after the evacuation.

House of Commons Speaker John Bercow was spotted alongside his deputy, former Labour MP Lyndsay Hoyle, next to Parliament Square where many of the evacuees had assembled. The historic Palace of Westminster, which was rebuilt after the the Great Fire of 1834, is facing disrepair.

A 2015 Independent Options Appraisal gave MPs and peers three options for a restoration: rolling works, a partial move out or a full move out, which would see parliament decamp to another site. The final option could cost taxpayers up to £3.9bn and would see the Palace of Westminster out of action for up to nine years.

"We have concluded that there is a clear and pressing need to tackle the work required to the Palace of Westminster and to do so in a comprehensive and strategic manner to prevent catastrophic failure in the next decade," the Joint Committee on the Palace of Westminster said in 2016.

"We have also concluded that, in principle, a full decant of the Palace of Westminster presents the best option under which to deliver this work.

"In our view, conducting the works in a single phase, involving a full decant, would allow the works to be completed in the shortest possible time frame, it would minimise the risk of disruption to the day-to-day operation of Parliament, it is likely to involve the lowest capital cost, it would minimise the risk to safety of construction operatives and occupants, it would minimise the risk to the Programme itself, and it would provide the greatest scope for meeting the needs of a 21st Century Parliament building."