The political and public campaign to force Britain’s banks to do more to help customers weather the economic downturn will gain impetus today with a promise from Royal Bank of Scotland to give at least six months’ breathing space to homeowners who fall behind with mortgage payments.

The promise, which will put pressure on other banks to make similar commitments, comes as ministers prepare to outline plans that could see voluntary codes of practice for the banking industry placed on a statutory footing.

The promise by RBS, which also owns NatWest, comes days after the government took ownership of a 58% stake in the bank after shareholders shunned the offer to buy new shares as part of the bank’s £20bn capital injection.

Financial Times