Seven per cent. That was the headline number that jumped out of this week's report from campaign group Better Finance shaming some fund managers. It found that percentage out of 2,332 funds in Europe are potentially closet index-trackers - meaning they charge for benchmark-beating performance while consistently failing to deliver it.

But there was a more interesting number that could point to a much bigger problem: 57% of the funds, known as Ucits funds after the EU regulation they comply with, did not provide enough information for Better Finance to be able to analyse them.