There might well be a few spare controllers at DSA or HUY but they wouldn`t be much use at LBA would they. It`s like saying Virgin are short of A340 captains so just stick a 747 pilot on it. Same job, no problem? MAN and LHR will have more controllers and operational positions so in times of staff shortage they will have more controllers available or will just shut down positions or sectors, incurring delays usually of more than the 30 minutes LBA was closed for but not actually closing. Controllers are expensive and take a fair while to train up so no airport will have a load just hanging around to cover all eventualities.