dontshootme. You really show your lack of knowledge/ignorance on the subject.
The cause of most of the delays at present is at Swanwick purely due to staff shortages and was forseeable by some 5/6 years ago. Well I can tell you that the night manning is as close to the wire as is possible and that is with ALL staff working ALL of BOTH nights. It only takes one person to be sick on a night and this often leads to closure of sectors. Indeed if more staff were to be available on nights then we wouldn't be in the crazy situation of having to re-route traffic out of the London FIR.
It still may be the case that staff at some units do get some sleep on nights-but don't long haul crews do so as well? Would you prefer to have controllers who have had no sleep at all controlling you at 0600 into LHR or someone who maybe has had a couple of hours nap?
It is an inescapeable fact as you put it that NATS has allowed in excess of 3000 days in lieu to accumulate at Swanwick alone and have no provision for the staff to take the time owing to them. So when you start criticising the working practices amongst the controllers,just have a look at what they have already given to the organisation first.