GWR Hall 4-6-0 No 5938 Stanley Hall with the 5.5pm Paddington-High Wycombe taking water from Ruislip troughs in the 1930s.
This is what happens of the fireman is a bit slow in raising the scoop below the tender when he's already got a full tender of water as the water will blow open the filler on the tender top drenching the first couple of coaches and their passengers if there are a few open windows !

Photo: F.R. Hebron / Rail Archive Stephenson