I assume that you have a keel cooled engine fitted to your narrow boat and as these have different specifications to the engines that we bring into the US, I have reached out to the boys at the factory in England to help you. Here is their reply;
For the control panel to remain on with keyswitch in off position / key removed, it sounds like the keyswitch has failed. Best to check this urgently before any other damage occurs. One quick check would be to switch off all power, photograph the rear of the keyswitch (so you have a record of what wire goes where) & remove wires from terminals: 30, permanent positive, normally 2.5mm brown/white to engine & thick white to stop button & ac, switched positive, normally small brown to engine & small white to panel positives. Once these two connections are free of wires, continuity check with keyswitch in off and then run positions. If all seems well & switch does look to be making & breaking correctly, check these terminals are not shorting out on anything in the panel hosing when fitted back in place.