Christmas TV ad spending up by £10m
http://www.guardian.co.uk/media/2007/dec/27/advertising.television

Christmas TV ad spend has surged by over £10m this year, fuelled by a surge in last-minute ads from panicked retailers worried about a sales downturn during the festive season . This surge has been driven by retailers and the "interior furnishing" category – brands such as DFS – which have contributed a rise in spending on Christmas ads of about £5m.
Media agencies and broadcasters have attributed much of the overall December boost to "late money" on ads to get consumers shopping on the high street.

Therefore most television channels will benefit as retailers will be looking to advertise during popular shows such as X -Factor, which have high ratings. As retailers want to reach mass audiences quickly.
However if one retailer advertises during a certain show, it is likely that others will follow. The rest of the article also highlights that the best performer in TV ad revenues has been multichannel TV which would include channel 4 and ITV