Other than everyone's mum, etc. It was clearly someone very, very important. There was a whole host of police motorcycles and cars escorting them and there were at least 2 police helicopters circling the area. Not exactly very subtle. You'd think it was the fucking queen considering how many police were escorting them (I don't think it was the queen).
So maybe like some head of state visiting London or something? Or even better, some high profile criminal? It was just now, I live by Mornington Crescent and they all came from the general direction of Tottenham Court Road etc and were going in the direction of King's Cross and so on.