(26 Jun 2021, 2:23 am)omnicity4659 wrote Companies have to register the maximum number of vehicles it wishes to keep at a depot, things like this are just amendments to the capacity. It may just be to house temporary buses or used as a contingency for years to come. Perhaps the decreases are getting rid of loaned or withdrawn vehicles.

Remember, it's just a theoretical capacity - it doesn't mean that's how many Stagecoach will actually be parking there.  An increase is a clue that there may be some service changes coming up that need more vehicles (a recent, significant, increase at Patchway in Bristol was a clue in advance that Stagecoach were having a bit of an assault on some of the local routes, and now have a decent permanent presence in the area!).  A decrease could imply the opposite, or they may just be disposing of surplus capacity that they haven't used for a while, as I guess it costs them for every nominal allocation whether or not it's actually used.