Originally Posted by
teflon
There's a little-known train fare called SailRail, which includes both your rail and ferry ticket to Belfast. From Glasgow, it's £27 one way - so slightly cheaper than the ferry fare you've found!.
Is it really that little-known - or am I just showing my age? :-)
Train tickets to destinations across the Irish Sea have always included the ferry crossing, for as long as I can remember. The ferries used to be run by the rail companies, and the trains to the ferry ports used to be called "boat trains".
The ferries are no longer operated by train companies, but the through ticketing arrangements have survived, both to Ireland and on the Harwich to Hoek van Holland route (which is local to me... and train stations around here are all displaying posters reminding travellers of "the train to Amsterdam" for only £-whatever-it-is)