Thank you
@Otis and
@43096 - 6M26 was the answer I was hoping for!
I didn't know about the RTT quick search trick for loco numbers, that's very useful.
In this case I thought it was 66788 I had seen and used location and time on RTT to confirm what the headcode was. I then looked at both the RTT and live.rail-record.co.uk sites to confirm the loco number but neither gave it when I went into the running details for that train/headcode. I have subsequently seen on my desktop that although there is not loco image with associated number as there would typically be for GWR, LNER, etc., it is there in text but it is hidden on mobile but can be revealed. This is really helpful to know and I could have used it many times before.
Vielen Dank