I have heard of this done before when the guys took off with high brake temps. If you pull the gear up then the temp falls much slower. I whon't comment on whether they should have taken off with high temps in the first place regarding perf and sop's. I have sat agast once though with my training Captain listening with interest when an F/O explained how they took off with 2 temps at 350 and just 'left the gear down to cool them a bit'. Find this hard to believe with Monarch though, very high standard of SOP's etc. They may have had an ecam indication, windshear warning etc wher they thought better just to climb up a bit before sorting things. When you raise the gear the doors open and in fact cause an increase in drag, if you have something happening windshear for instance then that's the last thing you want to do so you leave it be. One would have thought though they would have given some indication to ATC, but when you are climbing out of Birmingham and maybe you have a slight problem your RT could be effected.