A financial specialist has lost the latest round of a legal fight with a mortgage company which lawyers say could affect a million people who own buy-to-let properties.

Retired mortgage broker Mark Alexander, 47, of Shipdham, Norfolk, had complained that he was unfairly asked to pay more for a buy-to-let mortgage because the West Bromwich Mortgage Company classed him as an investor not a consumer.

The West Bromwich - which is linked to the West Bromwich Building Society - had said customers with three or more buy-to-let properties were not "regarded as consumers".

And bosses had disputed Mr Alexander's claim - arguing that the terms of an offer were fair.

A High Court judge today ruled in favour of the West Bromwich.

Mr Justice Teare rejected Mr Alexander's complaint about the way an interest rate had been varied at a High Court hearing in London.

But Mr Alexander said he was aiming to ask the Court of Appeal to consider the case.

About 400 other people who had identical mortgages with the West Bromwich had joined Mr Alexander in his High Court fight.

Lawyer Mark Smith, who represented Mr Alexander, estimated that around 15,000 West Bromwich customers could be affected. And he said as many as a million people in total could be affected throughout the UK.

"This is bad news for a lot of people," said Mr Smith, after today's hearing. "And it is good news for a lot of financial institutions."

He added: "We are considering an appeal."

Mr Smith, a barrister who works for Cotswold Barristers - which is based in Cheltenham. Gloucestershire , had told Mr Justice Teare: "(The case) is going to be a matter of interest to a large number of financial institutions as well as their customers."

The judge, who had analysed argument at a trial in London earlier this month, said he had been asked to consider whether the construction of a mortgage agreement was consistent with the terms of an offer.

He was told that the total costs of the case could be more than £450,000.

Mr Alexander - and his supporters - said they had had run up lawyers' bills of around £100,000.

The West Bromwich said its costs were about £370,000.

Mr Justice Teare said Mr Alexander - and his supporters - had lost and would have to foot all legal bills.

But he said the costs would need to be analysed and assessed and added: "I would be very surprised if anything like the figure of £370,000 ... could be justified as reasonable or proportionate."

Normally clients instruct solicitors who then instruct barristers.

But Mr Alexander had instructed a barrister himself using a direct-access scheme offered by Cotswold Barristers.

Mr Smith said the claim was the "single biggest direct-access case" heard in an English court.

Earlier this month, the UK's most senior judge had told lawyers that litigation costs must be ''proportionate''.

Lord Neuberger, President of the Supreme Court, said it was ''fine'' for rich men like Chelsea Football Club owner Roman Abramovich to spend millions of pounds on lawyers when fighting over hundreds of millions of pounds worth of assets

But he suggested, when delivering a lecture to barristers in Manchester, that people might be ''mad'' to contemplate litigation in some situations.