Hello I think this marking is the Guards Armoured Division 'ever open eye' and the truck got this by: Look at this also please,http://en.wikipedia.org/wiki/10th_Armoured_Division_(United_Kingdom), It shows 10th armoured was in Libya at this time 1950s I am starting to think along the lines of
The Armoured Brigade Signals Squadron was expanded to 10th Armd Div Signals in May-June 1956, based in Tripoli. It began to wind up in April 1957, and disbanded completely in September 1957.[9]