Poll: Should the Royal Family pay for work to Buckingham Palace?

Shadow business secretary Clive Lewis went even further, saying he felt the Royal Family could contribute "quite a bit" to the major restoration.

It comes as Chancellor Philip Hammond defended the outlay, saying such iconic buildings played an important role in Britain's soft power.

Speaking on BBC One's Andrew Marr Show, Mr McDonnell said: "It's a public building, it's a public monument, it's a heritage building, so we have to invest in it to preserve it.

"If the Queen and the Royal Family want to consider a contribution, I certainly wouldn't send the cheque back."

Asked whether the Royal Family should be paying for some of the work, Mr McDonnell replied: "That's for them to consider. I think we'd welcome it.

"I just say this gently as well. If it is a public building, it would be a nice touch if it was opened up free of charge to the public a bit more as well."

His shadow cabinet colleague, Mr Lewis, though, said refurbishing the palace would not be a priority of his.

He told ITV's Peston On Sunday: "If the Government do that, if they decide to do that, I think the Queen could contribute a little bit towards that.

The refit, described by officials as "essential", will include replacing boilers, and miles of cables, pipes and electrical wires.

Mr Hammond told Peston: "There's never a good time for government to announce that kind of spending.

"We've also got to spend some money, a very large sum of money on the Palace of Westminster.

"These are iconic heritage buildings, they are owned by the state, they are Grade I listed heritage buildings and they do play a very important role in supporting Britain's soft power projection across the world, in supporting our hugely important tourist industry here."

Labour's shadow work and pensions secretary Debbie Abrahams has also called on the Royal Family to "do the right thing" and contribute.

Ms Abrahams told Sky News' Murnaghan that while Buckingham Palace attracted lots of tourists, this had to be balanced against cuts to things like disability benefits.

She added: "I'm sure Her Majesty would want to do the right thing and contribute to that refurbishment as well."

The SNP's economics spokesman, Stewart Hosie, also told the programme: "I think the public will take a view on whether spending hundreds of millions on a royal palace is sensible when people are driving over potholes every day, or when the trains don't turn up on time.

"The SNP will take a view on that when that number's firm, when a decision has to be made."