GWR Double Slotting Instrument with brass plate 'No 1' affixed to the top. A wonderful instrument with two dials, each with a flag stating 'Slot Off - Wrong - Slot On' . The base has a brass switch either side and small oval plates 'Slot Batty Off' and 'Slot Batty On'. Interestingly, the makers name is stamped into the lower beading 'Marconi Wireless Makers Telegraph Co'.