I was at Victoria to see it arrive, about 19 late. Most of the enthusiasts there were under 18 and the atmosphere there was like a football match!
In your photo IMG_7512, I see on the TV screen on the far right, for the 19:36 West Croydon service, at the bottom it says "Class 455". I saw the same thing written on the older orange dot-matrix screens on that day (14 May).
Was this a one off addition on 14 May? I know that SE screens state the Class of train, but as an occasional Southern user, I haven't seen Southern screens state the Class of train.
If it was indeed a one off on 14 May, props to those who arranged it! Great attention to detail.
Great to see the large number of photographers out as well! I was at Waterloo East and Charing Cross. There was a small crowd at Waterloo East waiting for the train. And there was a large crowd at Charing Cross! Plenty of other photographers were also captured on video, based on the videos on this thread!
Anyway, on 14 May, I was on a Coulsdon Town train, and the PIS was showing "Welcome Aboard the Southern Service to London Bridge. The next station is Reedham. Welcome aboard this Class 455 Metro Marauder Railtour". I think it was a mistake, the Railtour part was confined to only Reedham station. The other stations didn't have the Railtour part.