Sorry to disagree but only very few LHR EF slots may be used to cover those american slots ex LGW. I understand that BA kept some slots ex BMed following its sale to BMI. I don't believe EF LHR recruitment to be directly linked to the IAH and DFW changes, yet I must admit I don't have all the facts.
Regarding the need for more WW crew in LHR, about 30-40 LGW crew are being transfered to LHR WW to balance manpower. The rest may be covered by PSR working down and some LHR EF transfers. BA have also replaced few crew ex LHR with extra International Cabin Crew on Indian routes, freeing more LHR WW main crew.
LondonPhilou, you say it right: things change very quickly and those who did not get 'the call' yet will probabily find out very soon anyway.
For those who can't wait, Qantas Cabin Crew London Ltd (not the real Qantas but close enough) are recruiting all the time. They have a very decent product, nice bunch, fab 74's, although money is not quite comparable to BA (but always worth the experience). Promotions are faster too, especially if you are already experienced crew, since they are based on merit rather than seniority. They would be my next choice if BA or NetJet were to show me the boot. I guess it's a matter of not letting your eggs rot in the same basket... Check the next best (or less worse)!
Ciao.