Sir David Tweedie looks at the grubby windows of his office with a wistful smile. The chairman of the International Accounting Standards Board has noticed they still bear the fingerprints of the children he invited in a few months earlier to watch the Lord Mayor of London’s annual show from what is an excellent vantage point, along the parade route just up the road from St Paul’s Cathedral.

The image of the kindly accounting chief entertaining a group of small children sits oddly with that held by many bankers: Tweedie, they claim, is one of the men responsible for exacerbating - if not causing - the financial crisis.