VS codeshare....
However, Virgin have had a long association with BE providing feed through LGW where required.
Whilst I agree that the outsourcing of VS domestic to EI may result in change for LHR connections, I doubt that Virgin Holidays have time to review the current set-up before S13, however next year could see a change I suppose.
Personally, I think that Virgin Holidays will keep with BE as there is probably greater value in the various LGW connections offered by BE on NCL, JER, GCI, IOM, BHD, INV and NQY compared to the Irish destinations that EI serve.