Yes, it was always a double edged sword with Manchester trying its hardest to lobby for greater non London air services, it could not justify then saying it and only it should have them, they had to say the lobby was for all the region airports and to that end, it was most successful.
What it was not allowed to do by law was crush Liverpool (which it could easily have done if allowed to bring its charges below them and outprice them) so Liverpool was allowed to artificially flourish at Manchester expense by law.
The same is not true for Heathrow which cross subsidised Stansted because they are all BAA (for the greater good of BAA) they have created a bigger monopoly, this was not envisaged when Stansted was given the go ahead to be expanded, the passenger numbers where capped at 7m and required to go back through Parliament to increase that figure.
The regional lobby agreed to this assuming that the figure would never get increased, unfortunately and again artificially it was, so it grew and grew, because it undercut all, and what could Manchester do? nothing its hands where tied because it was a regional monopoly airport.
Ironically several years before this Stansted threatened to report Manchester to the European Commission for attempting to attract traffic by undercutting Stansteds landing fees, how they have turned that round.