Question to the HM Treasury:

To ask Her Majesty's Government what is the latest cost estimate for the refurbishment of Buckingham Palace.

This question was answered on 29th October 2020
The reservicing of Buckingham Palace, which includes replacing the ageing core services of the Palace to eliminate the very real risk of fire or flood, is a ten-year programme started in 2017 with an agreed maximum budget of £369 million.

The official business of The Queen, including the current reserving of Buckingham Palace, is primarily funded through the Sovereign Grant. This is paid from the Consolidated Fund, but calculated by reference to The Crown Estate's profits (currently set at 25%). In return, The Crown Estate's revenue profits are paid into the Consolidated Fund.