A little bird tells me that this is being done as part of the deal to work more closely together, with VM helping Sky to try and minimise the projected loss of future income from Sky Sports.
These include security measures to try and counter card sharing, using a VM domestic subscription in commercial premises etc.
VM customers who have subscribed to Sky Sports in the past or have indicated an interest in the channels may be contacted by a third party company with incentives to subscribe again- hint, if you are called by them and are interested, don't accept straight away, they have a number of discounts at their disposal which increase to roughly half price
Some Sky channels have been moved on the VM EPG by mutual agreement.
In return for this co-operation, VM get to offer SS3 HD, SS4 HD, F1 HD and SSN HD to their customers with unprecedented access to Sky funded promotions.