I think only BBC has catch up in HD so yes that is normal for ITV which is why on the rare occasion I always record ITV and don't count on catch up as the quality of on demand of the other channels is awful
With the exception of BBC iPlayer content, which is delivered direct from the BBC's servers via the TiVO's internet modem, all other content is held on Virgin's own Headend servers. When an OD programme is requested, the programme is sent to the nearest street fibre node on a standard MPEG2 or MPEG4 broadcast stream, which is then only available to the TiVO initiating the request. There is only a finite amount of spectrum available for these streams, so if there is high demand for OD content in a local area, the system can become overloaded, especially with bandwidth hungry HD material. This may be one of the reasons there is less HD material available. The other may simply be the broadcasters themselves only releasing SD material to Virgin.
Cable customer since 1993. Services: FH TV, Sky Sports & Movies (2xV+), Talk Unlim Telco, VIVID 100, Virgin PAYG Mobile