Megan Butler is not what you expect from the Financial Conduct Authority, the powerful but staid UK watchdog that has handed out more than £250m of fines since the beginning of last year.

The 54-year-old former barrister looks like she might be more at home at a media agency in Soho than a regulatory body that has only recently relocated to Stratford, an up-and-coming but still unexceptional district of London.