Let the Train Take the Strain (Again)?

Something similar has been tried in France. The Intergenerational Foundation (IF) 'thinktank' note, that, in 2019, the UK's domestic aviation produced 2.7 megatonnes of carbon dioxide. IF determined that, if flights with a rail alternative under 4.5 hours in duration were banned, the UK's release of this 'greenhouse gas', would be very substantially reduced (https://www.theguardian.com/business/2022/oct/12/banning-flights-on-uk-routes-with-fast-rail-links-could-cut-flight-emissions-by-third). Replacing the plane by the train would reduce the UK's emissions by 885 kilotonnes, a 33% reduction. If only Great Britain was considered (there are no rail links between Northern Ireland and the rest of the UK), the saving would be more than 50%. This seems like a 'no-brainer'. One can't imagine, however, the approach being eagerly adopted by Ryanair. Rail ticket prices will have to be substantially reduced, if travellers have a choice between air and rail travel.