@dave_b check the pitch power has not tripped... Seen this quite often. May need to reset breaker....My cable is brand new, plugged in, hit the switch in the van and it does not turn on…the 12v light does not come on and the 3 pin plugs don’t work.
Maybe the outlet is not switched on at the pitch?
This also, mine trips occasionally - it's the inrush current tripping the consumer unit breaker.Has the consumer unit in your van tripped?
The box is locked……Lift the blue switch on the right - it's currently off.