A rare example of Great Western Railway early "split case" block bell , the description "split case" refers to the 2 front removable section of the instrument case which is held in place by 2 brass 0 BA screws. This system allowed for a Lineman to inspect or service the front of the instrument without removing the case so rendering the instrument inoperable. In practice it became clear any problems were usually at the rear of the instrument so these removable tops were phased out and replaced with a one peice lid. This instrument was manufactured by the G.W.R. at there signal works and the case is stamped twice, very rare to fine the base stamped in this way. The instrument is complete and tested and is in full working order.