I travelled home on the 27th the last two years. This year I spent an extra day in London (not entirely due to the traffic), so came on the 28th. I took my normal 5 hours (including break) even though I detoured via Wrexham as Junctions 14-15 of the M6 were heavily congested. My son drove from Bedford to Bromley on the 27th, and took my advice and allowed twice his normal time. As an ex-proffessional driver I can see no reason to drive at the worst possible date and time of the year.