From what I've heard, it was a Mildenhall-based aircraft inbound from the Azores with a, as stated, hydraulic problem. Due to cross-winds at its base they opted for EGLL, so must have been critical as I don't think the Mildenhall runway heading is more than 20-30 degrees different than Heafrow, correct me if I'm wrong. Suppose they could have had a completely different wind component at base.
Anyway, as long as everyone is safe then all's well.
Now, start the conspiracy theories....
