The Serious Fraud Office suffered a bloody nose yesterday, after a High Court judge granted the Tchenguiz brothers a judicial review into their arrests and the searches of their homes and offices in raids last year.
The three-day hearing has been scheduled for early May and could cast an unflattering light on the law agency's procedures.
Lord Justice Thomas, who has been critical of the SFO before, said that the review should cover the entire conduct of the inquiry into the brothers, which was launched after the failure of Kaupthing, the Icelandic bank. Both brothers had loans with the bank while Robert Tchenguiz was also its major shareholder.
They are already seeking damages of more than £100m for "wrongful arrest" as well as for the searches, but believe that "aggravated and exemplary" damages could now push this much higher.
The arrests were made in dawn raids in March on a day when the colourful brothers had been due to fly out to Cannes to host a party on their yacht at the Mipim show, an annual bunfight for the glitterati of the property world. Tchenguiz parties have become legendary for their glamour.
Vincent, the older of the two, has been regularly photographed with one or more beautiful women on his arm, although his brother Robert, the younger and maybe the smoother of the Iranian-born pair, has slowed down noticeably since his marriage.
The SFO swooped as part of its investigation into Kaupthing, which collapsed during the financial crisis.
Robert Tchenguiz was its biggest shareholder and a customer, while Vincent had taken out a loan with the bank several months before the collapse. The brothers furiously denied any wrongdoing, and neither has ever been charged.
Robert Tchenguiz said yesterday that he had repeatedly offered to co-operate with the SFO.