The three executives are said to be Anthony Alt, deputy chairman of the firm, Robert Leitao, the firm’s head of UK global financial advisory and its co-head of global investment banking, Nigel Higgins.

According to the lawsuit, filed in February and made public this week, the three executives invested in an unregulated collective investment called Film Development Partnership IV LLP on UBS and ProAct’s suggestion, said the report.

The publication said they were told that what was described in the suit as a “highly aggressive tax avoidance mechanism” was “all but certain to produce, by reason of the tax relief which would result, a return in excess of the investment.” According to the suit “such representation was false,” said the publication.

UBS allegedly didn’t warn the men of the risks of buying into the fund, which invested in film financing, distribution and development. The trio of executives are allegedly seeking a total of £1.25 million from UBS and ProAct Financial over the advice, which is said to date back to 2004, said the report.

A spokesperson for UBS told WealthBriefing "We are aware of the proceedings, and we will vigorously defend ourselves." Meanwhile Rothschild declined to comment when contacted by this publication.