Earlier quoted context omitted.
> fund new tunnelling is this supposed to be a double entendre ? I don't see how this follows from the parent comment.
The comment is making fun of a proposal Boris Johnson once made about building a bridge from Scotland to Northern Ireland, which is considered borderline physically impossible as far as I understand.
Tunnel, no. It’s very feasible and practical from a civil-engineering perspective, but the economic value of a road connection between NI and Scotland has not been demonstrated to outweigh the economic cost of its construction.