GWR 4-6-2 No 111 with its unique eight wheeled tender taking water at Old Oak Common shed in 1919.

Peter Kerslake says "Water is being taken by way of a conventional hinged filler but in its early days "The Great Bear" had been designed to replenish its tender by way of a hinged flap incorporated in the dome placed immediately above the intake pipe from the water scoop used on the water troughs.
This original design was soon changed after a number of incidents resulted in the flap bursting open whilst 111 was on the troughs, with water wrecking the leading corridor connection and cascading into the leading coaches, much to the alarm of the unfortunate passengers and not what Mr. Churchward had intended!
A revised design placed the dome, minus its flap, much further forward within the tender coal area/"

Photo: F.H. Stingemore / Rail Archive Stephenson