The great British bank boardroom experiment is over. The results are in and the conclusion is clear: banks that promote their chief executives to chairman fare better than those that don’t.

It doesn’t sound heretical. The idea banks should be run by people with banking experience is now a truism, driven home by parliamentary flayings of the former top executives at Royal Bank of Scotland and HBOS. But it goes against the general grain of the governance code – which makes listed companies that push their chief executives upstairs explain why.