i might have found it!!! the british fox armoured car was a post war 4x4 armoured car with a 30mm main gun.
found these pictures, i'll try to get some info.
http://www.ifrance.com/ArmyReco/europe/Angleterre/vehicules_a_roues/Ferret/Fox/Fox_Angleterre_diaporama.htm
false alarm, it seens it was built in the 70s-80s