Parliament restoration delays 'frustrating', says Commons Speaker

Sir Lindsay also questioned why a fire-suppressing mist system had not yet been introduced throughout the building, even though he has called for it for years.

"The major part and the most historic parts of the building haven't got it, and that's what we need."

Asked about reports that Parliament might be given an opportunity to vote on the way forward before the end of 2026, Sir Lindsay said that was a matter for government business managers.

"Who knows when it's going to come forward? Let's see what the House decides," he said.

Much of the 19th-Century building's network of wires and pipes dates back to the 1940s - and some to the Victorian era - according to a report, external which warned of an "impending crisis" a decade ago. Fire safety issues and high levels of asbestos have also been identified.

The BBC understands government whips have discussed holding a debate and vote by the new year, but no date has been scheduled.

This would decide whether to proceed with up to £3bn of initial works and narrow down four current options, ahead of a final decision by 2030.

One proposed option would see MPs and peers move out of the site for up to 24 years from 2032, costing up to £15.6bn.

Another involves moving only the House of Lords out of the building, costing £39bn and taking 61 years.

The chairman of the body in charge of refurbishing Parliament defended the potential costs earlier this year, telling the BBC: "We're already spending £150m a year trying to keep the thing standing."