RAF operations room raid block plaque '6' / '9'

Raid Designation Plaque, 1 Figure Series.  Air Ministry Reference No. 4M/42.  Headquarters Fighter Command Reference No. R.C.  Incredibly rare 'Raid Block' plaque/tile used in RAF Filter and Sector Operations Rooms during the Battle of Britain and beyond to display important information relating an enemy raid.  The raid block itself was normally positioned at the head of the plotting path and provided information such as strength, height and whether the aircraft were 'hostile', 'friendly' or 'unknown'.  This plaque measures approximately 1" x 0.5" /25 x 19mm and has the number '6'  (or '9' if inverted) printed in red on some form of early white plastic.  It would have been positioned on the raid block along with other tiles representing height, strength and so on.  It fits both the metal and wooden style blocks as shown but please note you are buying one single tile - the blocks are shown for illustrative purposes only.  These are the first 1-Figure Series plaques that we've been able to offer as they have eluded us until very recently.  Very limited numbers available.  Very good used condition.  A fantastic opportunity to create a small Operations Room display.  Stock code M29037.