Fantastic mate. I had a similar but slightly less dramatic experience. I was with a mate on the fence close to the Cannock Road signal box which was just north of Low Level station. The signal man, who turned out to be a guy that lived at the top of our street, recognized me and got us a ride on a the footplate of a little pannier tank engine that was running back to the shed. Not as grand as a King but like you say never to be forgotten.
One of the saddest sights sites I have seen was looking over the wall of Dunstall Park Station into Stafford Road shed yard and seeing all the King locomotives in a row, withdrawn from service never to run again. It was in 1961 I think.