Air Ministry Reference AM/255, Headquarters Fighter Command Stores Reference No. A.A.M. Incredibly rare Operations / Filter Room magnetic plotting 'counter' used to display important information relating to an enemy raid. When details of aircraft were received at Group Filter Room level, the information was interpreted on a map table using plotting 'counters' in the form of coloured arrows, discs and shields. Arrows indicated the direction of aircraft seen over land by Observers or over sea by radiolocation. Shields indicated aircraft heard over land or sea by Observers and discs indicated circling aircraft. The colour of the plotting pieces related directly to those on the Sector clock such that information was updated every 5 minutes. We have three 'red' circular counters, approximately 0.75"/2cm diameter, made from metal, painted red with a black stripe across the centre. There is minor paint loss but overall condition is good. Metal plotting pieces were positioned by WAAF plotters using a 'croupier' rod with a magnetic tip. A fantastic opportunity to create a small Battle of Britain Operations Room display. NB, map shown for display purposes only and the price shown is for a single counter. Stock code M25664/8.