Lord Hanningfield, David Chaytor, Jim Devine and Elliot Morley deny theft by false accounting.

They argue that parliamentary privilege should protect them from prosecution over allegations that they fiddled their expenses.

But in June, Mr Justice Saunders, sitting at Southwark Crown Court, rejected their claim, and today the Lord Chief Justice, Lord Judge, sitting with Lord Neuberger and Sir Anthony May, agreed.

Each of the four defendants, who are all on unconditional bail, face separate criminal trials as a result of the ruling.

But it is open to them to seek to take their case to the Supreme Court for a further challenge.

Former Bury North MP Chaytor, 60, of Todmorden, Lancashire, is accused of falsely claiming rent on a London flat he owned, falsely filing invoices for IT work and renting a property from his mother, against regulations.

Ex-Scunthorpe MP Morley, 58, of Winterton, North Lincolnshire, is charged with falsely claiming £30,428 in interest payments between 2004 and 2007 towards a mortgage on his home which he had already paid off.

Devine, 57, of Bathgate, West Lothian, formerly MP for Livingston, is accused of wrongly submitting two invoices worth a total of £5,505 for services provided by Armstrong Printing Limited.

He also faces a second charge alleging he dishonestly claimed cleaning and maintenance costs of £3,240 by submitting false invoices from Tom O'Donnell Hygiene and Cleaning Services.

And former Essex County Council leader Lord Hanningfield, who is also known as Paul White, 69, of West Hanningfield, near Chelmsford, Essex, faces six charges of making dishonest claims for travelling allowances.

Giving the judgment of the court, Lord Judge said: "It can confidently be stated that parliamentary privilege or immunity from criminal prosecution has never, ever attached to ordinary criminal activities by Members of Parliament."