Indeed Manchester is not a sleepy hollow, but nor does it handle anything like the level of traffic that LHR, LGW, LAX, JFK or other airfields familiar to BA pilots. I have been to Manchester many many times and could count on the fingers of one hand how often I've held, which compares rather favourably to the 90% chance of holding at LHR. I don't recall the exact details of whether a PAN call was made earlier, but sometimes events conspire to prevent one from doing so. It is a fairly regular occurence at LHR for an aircraft to be fine for fuel on the approach but need to declare a PAN or MAYDAY immediately in the event of a go around. Good airmanship dictates you advise them of that fact as early as possible but ATC seem to handle it just fine. As you are aware, there is no fuel priority procedure in the UK and the CAA would no doubt take a dim view if people started shouting PAN then landing with full reserves plus some on a regular basis. This aircraft landed with 5 tons. A typical reserve figure for the 744 is 4.5 tonnes. Technically the aircraft did not need to declare an emergency at all. The cause for concern was late uncertainty as to whether 3 tonnes of that fuel was usable or not. As it happens it was. 5 tonnes - not an emergency. 2 tonnes - very much an emergency. The declaration of a MAYDAY due to fuel state should leave ATC in no doubt as to the severity of the fuel state. Should it not, the request for a sterile runway represents the backstop. Manchester really isn't that hard a place to create a sterile runway and I have no doubt the ATC staff were able to do such rapidly and with much more spare capacity than an over-tired crew contemplating a three engine go around with potentially just two tonnes of usable fuel.
As to the question of would I prefer to perform the same procedure at another airfield with more fuel, yes of course. Perhaps St Johns? Or Keflavik? The aircraft went to Manchester because everything indicated it would get there satisfactorily. If it could only get to Glasgow then they'd have gone there. If they couldn't make it across the pond then they'd probably have gone to New York. The point is that until they were past these airfields there was no indication that continuing to Manchester would present any problems. BA is a commercial organisation and getting to the aircraft as close to London is a consideration once all other factors are considered which is probably why they elected to go to MAN instead of GLA at the planning stage. There is also the consideration that Manchester has two usable runways so that in the event of one being blocked on final approach with critical fuel a switch can be carried out relatively quickly and easily.