Tobzalp is not completely correct when he/she says the managers are ex-ATC's. 90% of the senior managers, those who call the shots on the bonuses for the middle managers, (the ex-ATCs) are accountants.
It's difficult to know whether the middle managers want more controllers, they simply aren't in a position to complain, however I have heard that a line manager (ATC) in one of the Centres has been virtually sacked for refusing to run the Group below it's full complement.
There also seems to be a push to get rid of anyone who has more than two years management experience. Most of the experienced Centre supervisors were given the shove in the last purge and the control tower management have just fired four senior tower team leaders. These people are the ones that grew up in an era when senior controllers did not take any **** from anyone, especially managers. They were responsible for air safety and they took their responsibilities very serously. They are of course being replaced by younger people who are more used to a book based ATC system (MATS is now four times thicker than twenty years ago) and are also used to the concept that "businesses need to be run by professional managers."
You'll have to forgive me but to me a "professional manager" is a dogs body who knows nothing about anything so manages "key performance indicators". Give me a managing professional anytime. Unfortunately they have all left the building.