Lord Keen: what were the events that led to Tory peer's resignation?

As Keen confirms he has quit as advocate general for Scotland, we look at how it happened

It was last week that questions over Lord Keen's position as one of the government's senior law advisers first emerged.

A three-page letter, marked official - sensitive", seen by the Guardian, revealed his serious reservations over Downing Street's intention to override the EU withdrawal agreement.