The credit crunch and ensuing financial crisis were inflamed by a breakdown of trust on a grand scale. In finance, abuse of trust is nowhere more corrosive than in the relationship between a bank and its clients. Among those relationships, the one between private bank and rich customer ought to be especially precious. That is what makes this week’s revelations about failings in UBS’s London-based international wealth management division during the boom particularly shocking and their implications far-reaching.

The Financial Services Authority fined UBS £8m for its failure to prevent employees carrying out unauthorised trades with customers’ money. Four as yet unnamed members of staff foisted more than $42.4m of losses (since reimbursed) on to unsuspecting customers until someone blew the whistle.