Every year when I was a toddler we went to Staithes (N. Yorks) - maybe 4/5 day trips every year. The engines were always big black tank engines (A8, A5?) - and every year, from around 1955/56, the engines got progressively dirtier and dirtier. This was very noticeable: even as a small child the lowering of standards was very obvious to me.
I’m guessing this was filmed on 8mm cine film, my late Father had some footage of steam trains around Mansfield, Nottinghamshire which was unfortunately lost during several moves along with the Kodak wind up camera and projector. So nice to see this 😀
