The Met "Farm" in the foreground and the RAF Jever Signals Square beyond - about 1956.   [Click to see the full explanation of an Air Traffic Control Signals Square.]   JV are RAF Jever's identification letters.   The symbols in the square mean the following: Red square top left-hand corner means "Aerodrome rules are temporarily suspended and that special arrangements are in operation".   This was the normal warning SATCO's used on RAF bases to warn aircraft that they were not welcome without prior clearance.   The H alongside means that there is an area set aside for Helicopter operations.   The red square in the right-hand corner with two yellow bars means land in an emergency only.   Again a protective measure by SATCOs to deter unwanted strangers.   The T just this side of that red square indicates wind from the right and therefore the landing direction is from left to right.   The white dumbell means that you must keep your aircraft on the paved surfaces (again a precaution) and the Red L superimposed means that light aircraft may take off and land on the runway or another designated area.   This area was the grass parallel to the runway.   (Thanks to John Hill.)