Aye, IIRC VM have been switching off all analogue services over their cable network for the past couple of years, as they used to provide channels 1-4 unencrypted (which could be picked up via a bypass on their installs and acted as an aerial for normal TV's*).
However a freeview box is useless with the VM cable as it's a completely different digital signal to the Cable Digital.
From memory a mirror subbed box with VM costs something like £5 a month to rent, and if you're on the Large or XL pack you can pay to get a HD box (something like £50 install, then the same monthly price as a normal additional box).
*From memory their analogue boxes often came with the bypass, but they stopped supplying them in about 05 for digital boxes.