Britain's biggest mortgage lenders were last night struggling to work out the details of a hastily arranged scheme designed to prop up the housing market and add lustre to an otherwise dull Queen's Speech.

Senior bankers were given just a day's notice of Gordon Brown's plan to offer a state-backed mortgage holiday to some families struggling with repayments, leaving a raft of details to be settled in coming weeks. Questions remain over who is eligible, how the scheme will operate, what effect it will have on the housing market, what compensation lenders will receive for lost interest and what liability will be assumed by taxpayers.