If by their own you mean one of numerous other cable companies that they purchased then yes. There used to be a plethora of small cable companies in the UK. Now there is only Virgin.
The widespread availability of high quality ADSL does seem to do a good job of keeping them honest though. I've been a pretty satisfied customer of them for many years now.
Virgin offer a "cable" service which is available where they have cable television (not a wide distribution area), and that this is what they refer to as their fibre service.
Virgin also resell the same ADSL that everyone else does (complete with BT line rental).
The widespread availability of high quality ADSL does seem to do a good job of keeping them honest though. I've been a pretty satisfied customer of them for many years now.