Here is the informed view.
In principle BA have agreed that should there be an excess of pilots in BACX then assuming that mainline were recruiting and that the BA secondees flying the RJ in BHX had no desire to return to Heathrow, that Pilots in BACX will be allowed to apply for mainline jobs.
However any selection will be done on a seniority basis and not the automatic selection of the particular pilots deemed surplus to requirements. Potential candidates will have to pass the BA selection process but will not have to undertake the sim ride.
All pilots taken on will be as 1st year pilots on the relevant payscale and more than likely employed on the shorthaul fleet.
Thats it in a nutshell and any other versions reported here are incorrect.