This post is in answer to Peter P B's question about this photo, www.ipernity.com/doc/grahamh/52557052 . That is, what is happening in that other photo. Look at the PiPs here.

Ash from the burnt coal accumulates in the smokebox. The mechanism highlighted here is a means to reduce a large build-up without having to open the smokebox door. Water from the boiler via the tap and pipe shown washes ash which is in the sump part of the ejector. Ash which is not in the sump can be moved into it using a pricker tool through the port halfway up the side of the smokebox in line with the sump. The pricker is moved around to get the ash to fall into the sump.

(A pricker is a locomotive fire tool. It is usually a steel rod with one end bent to be a handle and the other end has 20-30 cm bent at 90 degrees. Its main purpose is to move fire around in the firebox.)