Telegraph block instrument; Sykes' Lock and Block with integral semaphore indicator. Single-needle (red/lower-quadrant) block-indicator, mounted on a vertical brass finialled-post, in a brass-bezelled circular aperture. The bezel is engraved "W.R.Sykes Interlocking Signal Co. Ltd London". Underneath is a thick rectangular brass plate engraved "Up Windsor Local to West London Junc 62" and a circular brass-bezelled "Locked/Free" window. There is a back-box.