Scottish builder Derek Carlyle’s seven-year battle with the 82 per cent state-owned bank ended as the UK’s highest civil court decided that the lender had reneged on an agreement to provide Mr Carlyle with the second of two loans needed to develop two exclusive properties at Gleneagles.

A £1.4m loan to buy two plots in the Perthshire town was provided but a verbal agreement to supply Mr Carlyle with a further £700,000 to build was not followed through on leaving him with land he could do nothing with.

The plots were later repossessed by the bank and sold for £900,000.

The case has now been referred to a commercial judge at the Court of Session, with Mr Carlyle planning a £3m counter-claim for loss of profits. Mr Carlyle’s claims his plan had been to develop rental houses at the site in time for the 2014 Ryder Cup golf tournament.

Mr Carlyle’s solicitors said the case could have “far-reaching consequences” for the banking sector, with other banks potentially now open to similar actions.

The developer originally won a Court of Session decision against RBS, which ruled that the bank had a contractual obligation to provide £700,000 of development funding on top of the £1.4m provided in 2007 to buy two plots on the grounds of the Gleneagles Hotel.

That ruling was subsequently overturned on appeal, but the panel of five Lords at the Supreme Court has now unanimously sided with Mr Carlyle.

RBS, whose legal bill is estimated to have run to hundreds of thousands of pounds, is now open to a £3m counterclaim for loss of profits and future income from Mr Carlyle.

Cat McLean, Mr Carlyle’s solicitor and head of dispute resolution for MBM Commercial LLP, said the case could open up other banks to legal action.

She said: “This has been a long, hard battle for Derek, who has had his life put on hold for a number of years, but has stuck with the case with dogged determination in the face of numerous obstacles put in his way by RBS.

“It is a vindication of not only his position, but also gives hope to many individuals and businesses in the property and other sectors who have suffered at the hands of banks.

“It sends a message that banks are not beyond censure or free to do what they choose, regardless of the human consequences - they will face legal redress in the end.”