I did the overnight trip once in the days when there was a 9.30pm HSS service from Dun Laoghaire which got into Holyhead about 11.45pm, and even then there was a 2 hour wait for the 1.50am departure to Birmingham, which took about 3 hours. Transferring to the first train from Birmingham at about 5.30am, got you into Euston at 7.30am, but the train would have been packed with London commuters. So now it's only an hour longer and I'd say the first direct service from Holyhead to London at about 4.30am would be pleasant enough once you're on it.
If you've ever got time to waste in Holyhead during the day, may be worth doing a "reckie" and finding a patch of grass on the hill nearby the port, with a view to taking a sleeping bag, a bivvie bag and an alarm clock and getting a few hours shut eye. Not very sophisticated, but with a bit of sleep there, and a bit more on the train and you'll almost be as refreshed as you would if you'd got the first flight over there. And there's probably a shower somewhere in Euston station so you're ready for the day.
There are about 4 direct services from Holyhead to London between about 4.30am and 9.30am - it's a shame the 2.15am Stena service from Dublin port to Holyhead doesn't take foot passengers and make a good connection with one of them.
On the other hand with the coach at least you're not having to get on and off, and you can just fall asleep, and wake up in London. I'd say it would be awful if it was packed though - I'd hate to be forced to be in an aisle seat next to someone I didn't know.
Last edited by Eddie : 08-03-2011 at 23:08.