Fair point P7 but I will clarify my thoughts on this a bit;
All too often these days we are finding ourselves relying on peoples goodwill to stay beyond their published hours to make the operation work. The protections that are there to ensure Controller fatigue is limited are pushed and broken because of the situation on a more and more regular basis. Over the past 6 months I have seen problems on nights due to late traffic and a lack of staff more than at any other time since I have been at Heathrow. Historically we always had 4 people on a night shift and yes this was 5 years ago and it led to allot of inefficient use of staff. As you rightly say slots are becoming available at the shoulder periods of the day and therefore we need to look at the implications of that. 4 on nights is not a bad start, but my major concern for the other night was the lack of forethought to call in an AAVA to cover the traffic on the night shift. We were a phone call away from shutting Heathrow to all in coming traffic last Tuesday, this did not happen because we managed to bandbox GMP onto Ground 2 and contain it as best as possible. When things like this happen we need contingency staff be they rosterd or called in on an ad hoc basis. 3 on nights and the 'Commercial risk' that was accepted for that man power plan is no longer a valid situation. The Commercial Risk we accepted I argue was never ours to accept in the first place. At the end of the day it is the airlines that bear the brunt of any ATC staffing exasperated delays.