Why had you burned your bridges with Brize? If Luton couldn't accomodate you - then I can't see why you felt you couldn't go back to Brize.
Or - as you say, call Luton on box 2.
Maybe there isn't a direct line between the two airfields, but the previous controller may have been being uber helpful and looked up the number to call via a BT line, and maybe the other guy was too busy, had to go through a switch board or something like that
But - as you say the beauty of the UK system is that it is flexible, but the downside is that controllers don't have to provide the service you may want!!!!
louby