Just started a BA holiday (club class) in Mauritius with a departure on BA2063 LGW -MRU on Monday evening 6th March. The holiday had a miserable start due to what appears to be yet another BA cost cutting exercise. Things started to go downhill when the BA mobile website on my iPhone showed a 49min arrival delay in MRU but no delay on departure. Strange but not a big deal as these things happen, just irritating. As we were new to South Terminal I checked with lounge staff re time needed to get to gate. Told 10 minute walk and that boarding was on time and watch for gate announcements on screens. The Flight, BA2063, duly appeared on the board at 19:15 for the scheduled 20:20 departure. So at 19:20 decided to start the trek to the gate as in previous years this flight has loaded quickly and actually departed the gate early so felt best to be in the departure lounge with plenty of time to spare. Shame when the lounge was so nice, but it appeared to be the last flight of the evening and lounge staff appeared to be getting ready to close up and most of the other pax had already left..... Got to the gate at about 19:30 with a whole bunch of other world Traveller passengers who of course were all being allowed to use the fast track lane into the holding gate, and as is often the case were not being stopped by BA staff, so this resulted in an unnecessary queue for Club and BAEC pax to get into the departure lounge. Very noisy, unlike the new BA lounge, as loads of very young children on the flight but Plenty of space so found a seat and waited for what we expected to be no more than 15/ 20 mins wait as the flight was still showing as departing on time. At about the time when boarding should have normally started we got a barely audible announcement to the effect that boarding would be delayed for about 10 minutes as they were "finishing off the cleaning of the aircraft". Still no big deal as these things happen. With nothing better to do I looked at the plane parked outside to get its reg no YMMC and then nerdishly went onto the basource website to see if I could work out where it had arrived from to see how late it had been inbound as assumed that was the reason for the cleaning delay. I could thus calculate roughly how long the delay might really be as I suspected that the 49 minute arrival delay was actually something to do with the inbound aircraft being late which would give an idea as to how long the boarding delay might be. I established that it had come in from Male but only 5 minutes late so that was unlikely to be the real reason for a delay. I then looked up the BA main website flight track for our flight and it was now showing our departure at 21.09 so that concurred with the delayed arrival but didn't agree with the BA mobile site or any of the repeated another 10 minute excuses being given out by the gate staff. Clearly someone at BA knew exactly what was happening but had failed to tell the gate staff who just kept churning out the cleaning excuse every 10 minutes to say it would be another ten minutes. This 10 minute delay nonsense went on for nearly an hour. Should have stayed in the lounge I kept telling myself! Anyway boarding eventually started roughly 50 minutes late and again no fast track line to the boarding gate as there were no BA staff policing the boarding gate other than to get all the families on board first (never quite understand why they do this as it only holds up everyone else!) So ended up halfway back in the queue to get on the plane. Settled into seat eventually and thought no more of the delay. However after about 10 minutes the First Officer came on the intercom to welcome us on board etc. Quickly followed by an abject apology for the delay which it turns out indeed was due to the fact that BA had recently changed its aircraft cleaning contractors (he didn't say whether this was a cost cutting measure but I suspect so) and either they hadn't turned up at all or couldn't do the job so he advised that the poor cabin crew "had donned their Marigolds" and done the cleaning themselves. This probably accounted for the spartan cleaning effort with seat covered in crumbs and inside of windows pretty grubby. Eventually departed 50 minutes late. On board service ok though food not great. steak way over cooked and more like braised beef (I appreciate you can't do steaks to order or underdone due galley and health issues but this was so overdone as to be almost inedible. Rest of meal ok. Slept ok, however after being woken up as normal 2 hours out of MRU we were told that some of the 3 club toilets were blocked and only one in use. Then shortly after that we were advised that every toilet on the plane was closed as apparently the cleaners (or someone) hadn't emptied the toilet tanks at LGW.! So everyone endured a pretty uncomfortable last two hours especially as this was a 12 hour flight! Most people on waking up usually want to use the toilet!!!! Funnily enough almost as soon as the toilets went awol the seat belt sign was turned on! About an hour out from MRU the first officer came on to apologise about the toilets and said he was pretty cross and would ensure the matter was fed back to ops at LGW, however that doesn't get over the fact that myself and my wife (a nervous flyer at the best of times) and I suspect most other pax had to spend two hours with their legs crossed due to inefficient BA cleaning at LGW. If there was a problem at LGW how come the captain allowed the 12 hour flight to depart without the toilet tanks being emptied? It makes you wonder whether the rest of the plane was properly checked maintenance wise. The cynic in me thinks probably to avoid having to pay out for an over 3hour compensation claim! Personally I would have preferred a longer delay and get the toilet tanks emptied before departing on a 12 hour flight! Communications at LGW were also far from satisfactory....Have lodged a complaint with BA but so far just offered 10k avios as compensation and advised its captains call to depart with almost full toilet tanks and is not a safety issue! Maybe but it's certainly a comfort issue. Also stated that they had received many complaints regarding this flight.