[James2001]

ITV did have one pretty big lapse in that regard.  The logo for the ITV network as a whole, often seen on trails for a new season or at Christmas:

www.youtube.com 

That was replaced in 1989 with the big "get ready for ITV" promo, but the old one remained on the ITV Schools on Channel 4/S4C service. Presumably the cost of redoing the animated graphics was considered prohibitive.

I'm not sure that ITV logo was ever entirely official anyway, even though it did appear on various promos (especially on Channel 4) and ITV Schools. I think the 1989 logo was the first proper official ITV logo, and I think there were a couple of other unofficial logos pre-1989 (I know the IBA had one they used as well). I think it was mostly Central (and ATV before 1982) that used it (and of course they were the ones responsible for ITV Schools).