The GB government is musing on the idea of such from Portpatrick across the Irish Set to Larne. Does not mean it will automatically happen but generally looked at on national transport matters.An awful long time ago trains went beyond Stranraer to Portpatrick but eventually line closed and replaced for a long time by the town of Stranraer.
For a long time when trains went into the town getting on the ferry to N.I. was only yards from the station and very convenient. However that has ceased and if say on a train from Glasgow you now have to get a bus several miles up the coast to board a ship! Back in the time of the 2nd World War there was actually a single line up to there for military purposes but lifted after the war and maybe that should have been brought back?
Does not mean it will automatically happen
I'm not a gambling man but I would bet money on it that it will never happen.
We covered this 10 years ago (http://web.archive.org/web/20131110202929/http://my.opera.com/community/forums/topic.dml?id=358901).
An Ireland-Britain link got almost as many votes as an Ireland-US link.
Of these, the Fehmarn Belt Fixed Link (https://www.skyscrapercity.com/threads/fehmarn-belt-fixed-link.492660/) is the one likely to begin construction by 2025.
Would say like such things over at Denmark,l etc would be a great addition but the main decision I will say a negative one as would be very highly expensive.
A more locally disappointmen is the changes mad to the ferry service which used to be at Stranraer next the station. If the Edinburgh government had brought back that line extension that used to be from Stranraer the several miles to the other dock that would be a positive. If travelling on an existing bus service for say Belfast you can go that drag to the change north of Stranraer but if travelling by train from Glasgow to Stranraer station you have to go for a local bus or hire a taxi.
Even over in N. Ireland which I have visited for years one shipping company moved from the centre of Belfast miles away but I still think that rail link at Straer being back is a positive and would be cheaper than a bridge across the sea!
Leaving aside the political hee-haw and the crossing mentioned in passing re a separate thread I actually don't think a crossing would be built as far too expensive alog with less of a population contrast. Being a railway fan gimme the former line from Stranraer back!