My knowledge of routes in the area is far too rudimentary to argue about the pros and cons of the Hyndland Loop, etc above. But there is, of course (as most will know in here) a perfectly acceptable alternative route via Kilmarnock and Dumfries just sitting there, virtually unused (at least south of Kilmarnock) on a Sunday.
In the bad days of BR, nobody would have dreamt of hiring in buses. Crews and stock would have been sourced, and trains sent via the G&SW. Maybe not every service, but enough would have been sorted out to keep the punters sort of happy. Today, it seems the first default option was buses.
This could still be done - but whoever Virgin is these days decide not to train crews etc to enable this sort of effort to ge in in emergency. Same with the S&C - they simply don't want to be bothered with preparing to use alternative routes.
This is, ultimatley, the fault of the regulator, who conspires with the TOC for short-term, cheaper if you are lucky, solutions.
Ah! Should have looked at RTT before opening my big keyboard
I see they did manage to extend quite a few Scotrail services today on the G&SW. Congratulations to the operators. I take it back.