The four include prominent left-wing barrister Michael Mansfield, a leading campaigner over miscarraiges of justice and a regular media pundit
The clerk to the Parliaments, Michael Davies, is said to have refused to allow the payments because he believed they were too high. This was after three of the four had already been cut, in some cases by almost half, by another official.
Fees in the fourth case are expected not to be sanctioned, though the process has not been completed.
Mr Mansfield, and the other three - Christopher Sallon, Peter Feinberg and Richard Henriques - are believed to have instructed a fellow QC, James Munby, to defend the amounts they claimed for appeals in the House of Lords last year.
The importance attached to the case by the Bar Council is reflected in the choice of Sydney Kentridge, QC, the most sought-after advocate at the Bar, to represent the profession.
The result of the inquiry, which will be held before five law lords on June 17 and 18, could be a dramatic drop in QC's earnings. Currently top silks earn around pounds 300,000 annually but payments could be brought into line with other professionals paid from public funds.
Mr Henriques earned the most out of all QC's from legal aid in 1995-96 with more than pounds 500,000 - although he later said that related to more than one year. Mr Feinberg was in the 1996-97 top 20 with earnings between pounds 350,000 and pounds 399,000.
At the inquiry, Law Lords will decide for the first time whether barristers' legal fees should be linked to a comparable sum for private work or whether it ought to be based on an income for a public service professional with comparable skills to a lawyer.
The obvious comparison would be with hospital consultants, who earn a maximum of around pounds 110,000.
The Law Lords will have to take into account the fact that since barristers are self-employed they have to pay chambers expenses and make their own pension provisions. This would would lead to a maximum figure of around pounds 175,000 for a QC's annual salary.Reuse content