Right, but that requires spending at least three hours on a ferry, therefore contradicting the concept of the title.
The other option might be ferries that carry trains. I believe they don't do this across the Irish Sea, but I've been on a train that drives onto a ferry across the Baltic sea connecting Berlin and Malmo (Sweden). You can get off the train while on the ferry, but you don't have to.
I take this ferry every few months and it takes a minimum of 1hr 50mins on a good day.
>The other option might be ferries that carry trains.
Not between Ireland and England.
My point is, I can get a train direct to any major airport in London and fly to a significant chunk of Europe in under 2hrs and continue my journey via train so why not factor in those options too?
This is why Eurostar to Paris/Brussels is so nice. Get on train in centre of London. Only need to turn up 20-30mins before departure and arrive right in the city centre at the other end.