S4R starter problem

Any wise folk out there maybe throw some light on this evenings show stopper? Been out for an hour, nothing too harsh, slowing for some lights and the motor cut out. All the lights are on, good battery, hit the starter, contractor clicks and all the right noise but no cranking. Had a quick look over the general wiring round the battery/ starter/ contactor etc, nothing unconnected or loose. Up until the stoppage, all normal.
Cheers