Baillie Gifford will take an industry lead this week by publishing 'active share' figures for its retail funds, amid criticism of many fund firms for charging active management fees for index-tracker funds in disguise.

The active share is the percentage of a fund's holdings that differs from its benchmark, giving an indication of how actively managed it is.

A 2013 report from SCM Private claimed that nearly half of all UK equity funds were guilty of being "closet trackers", charging higher fees than tracker funds but not differing significantly from their benchmark index.

Earlier this week the Financial Conduct Authority was reported to be considering whether or not to investigate.

Now Baillie Gifford has said the active share for its funds at the end of 2014 ranged from 69per cent for its Greater China Fund to 99per cent for the Global Discovery Fund.

Its flagship investment trust the £3bn Scottish Mortgage has a 95per cent active share and the lowest among its seven trusts is 83per cent at Pacific Horizon.

James Budden, the firm's director of retail marketing and distribution at Baillie Gifford, said: "We are passionate about the value of truly active management and recognise the need for investors to be able to identify an actively managed fund from in-and-amongst the shoal of 'closet tracker' funds. You can only outperform by being different from the index. Anything over 60per cent suggests you are on the right track."