Didn’t it not always start around 10:30? Gameshow at 9:25 - 9:50/55, followed by The Time, The Place before This Morning?
ITV daytime had a revamp in the spring of 1998, which saw the end of the 9.25 quiz. The new schedule had a "preview" of This Morning at 9.25 - ie, just an extended trailer - followed by Vanessa at 9.30 and then This Morning at 10.10. Then over the next few months Vanessa/Trisha got longer and eventually filled the whole hour (I wonder if the first few months were just looser edits of episodes intended for the previous half hour slot in the afternoon) so This Morning moved back to 10.30, and the "preview" at 9.25 also went for a burton.
As I mentioned a while back, during the Twiggy and Coleen reign of terror, the end time moved to 12.00 as it was being absolutely thrashed by Bargain Hunt, before it moved back to finishing at 12.30.
It's at this point I also mention the brilliant 2000 ITV daytime revamp to coincide with the launch of Doctors on BBC1, where they moved Jerry Springer to 9.25, Loose Women to half an hour at 10am and Trisha to 2pm. And then four weeks later moved them all back again because the ratings plummeted.