Delay to Parliament repairs as ministers pass the buck

can reveal. Ministers are preparing to announce the creation of a separate authority to investigate proposals for moving MPs and peers out of the Palace of Westminster during the renovations.

They want an outside group of experts to scrutinise the costs and details, but that process could take several years to complete because of the scale of the refurbishment.

It means that the final binding vote on what should happen to the building may not occur until as late as 2020. Ministers’ refusal to select a proposal themselves is likely to create a backlash from MPs and peers, who warn the building is so unsafe it could suffer a “sudden, catastrophic failure”.

The announcement, scheduled for May, will also trigger accusations that the Government has delayed making a decision in the face of a Tory rebellion.

Chris Bryant, the Labour MP, said: “We have got to choose the quickest, safest and cheapest option and we can’t run away from making a decision now. The building is in peril.” Refurbishment has been under discussion for years, as the building – rebuilt after the fire of 1834 – is in a state of disrepair.

Last year a committee of peers and MPs endorsed the boldest of three options, opting for a “full decant” that would move out both the Commons and the Lords for six years. The proposal would be the cheapest – costing between £3.5billion and £3.9billion – but is opposed by some MPs.

The two other options are for MPs and peers to take it in turns to move out, a state of affairs which would last for 11 years and cost £4billion, or for a “rolling programme” of works, which would take 32 years and cost £5.7billion.

A decision has been pushed back repeatedly. This newspaper understands that plans are to be handed over to an arms-length “delivery authority”, similar to the one used for the London 2012 Olympics, before a binding vote. “The key thing for the authority is to look at all the costs and risks before we make a final decision,” said a senior government source. A group of sponsors will also sit above the authority, including political figures and possibly people who have experience in heritage.

The Joint Committee on the Palace of Westminster report on refurbishment, published last September, warned of the risk of delay: “The building might suffer a sudden, catastrophic failure.”