61306 Mayflower and D1015 Western Champion seen THUNDERING down the English Riviera Line (01/06/24) 

I think there was a 150 not far in front of it.

From what it looks like on RTT 2T15, it was ahead of it and that one was running late

Previous train still in section. JG.

Don't want Champion showing the modern engines up. That would never do.

It was in both clips of D1015 - occasionally they change its name to a former classmate's name so this time it was D1011 Western Thunderer. You can search for some of its older tours and you'll find it did the same with other numbers as well, more commonly when it was in its maroon livery.