Yes, Sheffield is ideally placed for access to Manchester Airport with hourly Transpennine Expresses taking 74 mins. The alternative is to take EMT to St Pancras (journey time just over 2 hrs) but then you have to trek right out to Heathrow.
Thanks for clarification. Yes I would imagine that, of the three routes, Edinburgh is the best performer. Business and leisure travel is healthy all year round and the Festival will soon be starting. Also Edinburgh isn’t served by any Gulf or Asian carriers which might syphon off east-bound long distance travellers.