LN,
Still not getting it.
All the pros of train apply to OSL, MAN & STN, it is just some of the numbers that are different.
Last time I checked, frequency from Piccadilly to MAN was such that the timetables just said "frequent services". Essentially c. 10 tph v. 4 to OSL.
Afaik, Flytoget runs in a straight line - it doesn't branch off. Off the top of my head, destinations with a direct link to MAN include Liverpool, Preston, Windemere, Edinburgh, Sheffield, Leeds.... and even Crewe in the other direction.
If people are going to use the train as an alternative to flying (e.g. very viable now across almost the whole spine of Italy) then the most important factor is speed. If they are using a train to get to the airport as an alternative to driving, then frequency and convenience are key.
MAN is within the GMPTE zone - a single from Picadilly to MAN is much less than an equivalent journey to OSL.
One change from MAN gets you to very large parts of the UK.
I think the difference between MAN (or substitute any UK airport) has more to do with mentality - we (not me personally, I don't drive, but Brits in general) love our cars - the Scandinavians are more happy to leave the car at home.
As for the politics and the CO2 argument, I think the journey to the airport is a fraction of the flight itself - unless you are alone driving a hummer from Thurso to catch a full shuttle flight to London! Public transport to airports reduces local air pollution - where conversely, cars not planes are the biggest offenders; and reduces traffic. Where that power is generated is again a rather small part of the picture.
If we really want to reduce our passenger transport emissions, then the answer is to substitute as many short haul flights as possible with high speed or medium speed high frequency rail. HS2 won't make much difference here as going to Brum won't substitute a single flight and the existing upgrade to the WCML has already swung the modal split @MAN in favour of the train. LCY-MAN & LPL gone, obviously helped by the double dosage of APD too!
HS2 would need to continue to Scotland to be really useful from a CO2 perspective but the political will isn't there, so we get a half-way solution with 1/4 of the value.