Jean Ford should check with her partner's marina. (Short term licence.) It all depends on the water.
In the basin where I used to moor, as the canal society whose water it was, restored the basin themselves, boat licences were not required. Insurance, BSC etc were required by the society in case of accident.
However, if the boat did not go out on to the main line, it did not need to be licenced. So in the case of someone refitting or just pootling around in the basin, they could avoid paying CaRT or before that BW.
I do not suppose for a moment that this situation is unique, there must be others to which this rule applies.
Tony Collins.