The building is actually cabled out for Sky, so my simplistic understanding is that Virgin just need to run a short length of cable from the CATV point out the front, to the main riser in the building and then terminate a box at each level. From there, it's a simple choice to connect the cabling that ALREADY exists from the power cupboard on each floor - to either 1) Sky or 2) Virgin.
If it were my business and that's all I had to do to obtain 40 or 50 new customers, I know what choice I would make.....
Anyway - hopefully someone from Virgin will formally contact me and make an appraisal.