The one thing we all know about investing is that past performance isn't a good guide to future returns. So it seems strange that EU regulators are forcing fund managers to use it against their will.

There have been rumblings of discontent about the EU's latest rulebook covering fund sales for some time now — but this week it turned serious. On Monday, Baillie Gifford, one of the UK's biggest and best-regarded active stock-pickers, issued a rare public warning that investors were being "misled" and wrote to the UK's Financial Conduct Authority to tell it so.