When one of London’s most senior barristers concluded in November that no officials at the Bank of England had been involved in any unlawful or improper behaviour in the foreign exchange market, the central bank might well have hoped to move on.

But despite Lord Grabiner's exoneration of the bank, the scandal continues to cast a dark shadow over Threadneedle Street. After tense encounters with Grabiner and bank governor Mark Carney in recent weeks, MPs on the House of Commons Treasury Committee are now considering whether the investigation probed deep enough - and if not, what they should do about it.