The taxpayer faces a bill of up to £7.1bn to stop the Palace of Westminster falling down unless MPs and peers agree to move out while the work takes place, according to a report.
A study by independent consultants has highlighted the appalling condition of Parliament - with potentially deadly fire risks, collapsing roofs, crumbling walls, leaking pipes, and large quantities of asbestos.
If politicians refuse to leave the building, patching it up to basic standards will take around 32 years and could cost between £4.9bn and £7.1bn.
Even if they relocate to another venue and allow renovation teams a free run of the historic site, it will still need six years and an estimated £3.5bn capital outlay.
The eye-watering sums were calculated by external experts.