Not that this helps to answer the original question but adds to inconsistancy.
On sunday gone BA400 to Brussels an A321 had a problem with door 3L when it was placed in automatic. Net result was the Captain announced that according to his rule book he could not fly and he had confirmed this with the ground people.
We went to a remote stand where the engineers confirmed and resolved the issue ^ but seeing as this was the Sunday with the ATC failure BA decided to cancel the flight (just after the last BA and BD flights had left) .... my long story of 17 hours to Brussels ....
(note I don't mind a flight being cancelled for tech reasons on safety equipment (would anyone want to fly on it?), I do mind when they cancel it when they have just finished fixing the plane)