Originally approved in 2022 at £6.1m, the bill has now soared to £9.6m. Peers say the door, installed by specialist restoration firm DBR, is “a complete white elephant” and still doesn’t open automatically, leaving even wheelchair users unable to enter without help.

Delays and cost increases were blamed on structural issues, the discovery of buried vaults, rescheduled work due to ceremonial events, and attempts to reduce disruption. Despite this, the door now needs someone stationed full-time to press a button to open it.

Lord Forsyth called the situation unacceptable. “It may be the most expensive front door in the world – and it doesn’t even work,” he told The Times. Labour’s Lord Berkeley criticised the design as untested and questioned why Parliament was being used as a “guinea pig.”

Leader of the Lords, Baroness Smith, admitted the door’s operation and cost were unacceptable but stressed the importance of security and heritage concerns.

The door was part of a wider security review following the 2017 Westminster terror attack. The Lords claim that ongoing issues are being resolved at no extra public cost.