Interestingly, I was playing golf under the LHR approach from about 1300-1630 local, and there were large gaps in the landing traffic quite frequently. I'm talking of up to 5 minutes between landers at about 1400 local. Very unusual - thought for a while they'd switched to easterly ops, but do departures either. Then the landers re-commenced.
I suspect that LHR had looked at the wx and decided to stop all near European a/c they could resulting in a shortage of aircraft when the CB's cleared through to the north at about 1430.