why bbc sport was fine on my new lcd toshiba but itv1 was so no good?

The likely reason is that either your aerial is pointing wrong, so if you turn it round you will get better reception from ITVand can be solved by trial and error, or there is something screening signal from the ITV transmitter to where your TV is, such as a high building near you and your aerial needs putting higher?

May be if you fit an outside aerial instead of an indoor one and point it in the same direction as you see other aerials around pointing, you will then get good signal in future.

But if you really want to get good sport on TV best way is to get a satellite receiver, and you can then get all the Sky Sports channels and Eurosport as well as BBC, ITV and Channels 4 and 5, all received equally perfectly?