Novice drivers who do not hold a full driving licence are permitted to tow provided that all conditions such as eyesight requirements and insurance are met.
Years ago when I was learning to drive Class I articulated HGVs I'd cut my teeth on light vans, seven and a half tonners, then a Class 3 vehicle which was a 4 wheel HGV up to 16 tonnes before graduating to the big wheelers, all at the company's expense natch :lol:
It helped that my then father in law (rest his soul) was a director of the company
When I was trundling round driving an unladen artic, the guy who was sharing the instructors time with me and who worked for a local council didn't have a full driving licence, so in addition to the large HGV learner plates the truck also displayed normal car L plates.
Obviously he was used to driving a car under supervision but hadn't passed his driving test at the time so in effect he killed two birds with one stone.
Perhaps the lady hadn't got a full UK driving licence or maybe she was trying for a B+E qualification under supervision?