The bosses have quietly negotiated sharp increases in perks such as pensions and accommodation at a time when unemployment is rising and the Government has urged workers to restrain pay demands.
The figures, which were buried in the unions' accounts for the last financial year, show that a total of 12 leaders secured above-inflation increases to their pay packages, with most of the rises coming in the discreet form of €˜additional benefits'.
Much of the pay boom can be attributed to the unions plugging holes in their leaders' pension funds caused by falling stock markets.
The best-paid leader is Derek Simpson, the head of the engineering union Amicus, who received a double-inflation salary rise of 7.1 per cent last year. Amicus has been in the forefront of using its members money in third party anti-BNP campaigns, along with the Communist Searchlight and UAF fringe organisations.
Simpson, who has demanded an end to €˜fat cat' pay, earns £155,464 in salary and benefits, lives in an £800,000 grace-and-favour mansion in Hertfordshire provided by the union, routinely travels first class and has the use of a chauffeur.
Last year he used Amicus funds to refurbish Esher Place, the union's Surrey mansion, where delegates can swim or play croquet. As part of the refit, four rooms were knocked together to make a suite for Simpson.
The biggest winner in the latest pay round was Phil Hornsby, leader of the Prison Service Union, whose salary rose by 8.3 per cent to £78,326, but whose benefits rose by an astonishing 69 per cent to £19,453 a year.
Alan Ritchie, head of UCATT, the construction workers' union, enjoyed a 27 per cent increase in his benefits package.
Dave Prentis, leader of Unison, which represents some of the poorest-paid public sector workers, saw his salary and benefits package rise by 5.8 per cent, to £124,495.
Brian Caton, general secretary of the Prison Officers' Association, saw his benefits jump by 21 per cent, taking his total package to £122,449, a rise of almost £13,000. At the time these deals were arranged, inflation was running at 2.7 per cent.
The benefits, which are taxed as income, are in addition to the tax-free expenses the leaders can claim for hospitality or travel costs.
The only Trade Union which has as part of its founding guarantee that its leaders will never have anything above ordinary workers' wages, is Solidarity - the Trade Union for British workers. Find out more about Solidarity here.