To get from Llanelli to Shrewsbury only takes around 25 minutes longer via the Heart of Wales (including all the stops) than going the longer way via The Marches. So, in the event of a closure on The Marches, it surely would be sensible to have the HoW cleared for 197’s in passenger use? If The Marches were closed for some reason and the Heart of Wales remained as just one or two coach 153’s, it would never cope with the numbers of passengers trying to get between SW Wales and Shrewsbury and beyond. Being as very long special trains occasionally go along the HoW, I see no reason why long rakes of 197’s could not use the route with passengers in an emergency.