I feel a bit sorry that you have had such a poor response to a perfectly valid enquiry, so I thought I'd write something for you.
The wife of a friend of mine has been a Passenger Services Agent at LHR for VS since 1994, and she loves it. Due to family commitments, she has turned down many promotions, and is happy just to continue on check-in rather than take on responsibilty, but the opportunities are there.
Generally, working for VS at LHR is really hard work, so don't expect an easy ride. The turnover of staff is high due to the travelling/parking problems and the shifts mean that you might only be working with the same person once every six weeks which means you don't get much of a chance to 'bond' with your colleagues. My contact has been at Gatwick for over ten years which means she is a 'known' face to everyone from loaders to Captains, and despatchers to 'RB' himself.
Generally, the working environment is easy going, and the emphasis seems to be on having fun whilst 'getting the job done'.
Generally, VS pax tend to be a pleasant bunch, and not too demanding. I have a few chums who work with me here at LGW for VS, but the clientele here is a bit different... chavs going to MCO on the VS27/15 to see 'Mickaaaaaaaaaaaaaaaaay'. That lot tend to be very demanding and extremely rude.
VS at LGW are handled by Groundstar/Swissport who took over from Aviance (GHI/BMI amalgamation) in March 2004. The GS agents wear VS uniform. There are a number of passenger services agents employed by the airline, but their role is mainly to oversee the handling agents.
If you are serious about a career in the airline industry, I would highly recommend VS as a viable employer. I have yet to meet anyone who has had a bad experience with Virgin Atlantic.
Good luck.
