A few comments about agricultural vehicles.
The idea of there being a limit of a few miles is a new one to me: my grandson & his father run an agricultural contracting business and travel many miles between jobs, 50 miles being for one of them. And they run on on red diesel.
Another problem, which basic Plod doesn't necessarily know about, is that provided all tractors are fully registered and owned by the firm, and all trailers are also fully owned by the firm, then any tractor can tow any trailer even if the registration details between tractor & trailer do not match. Son-in-law did indeed get pulled up for that and despite explaining to basic Plod, he was summonsed, or what ever basic Plod does, only for the Sergeant to confirm that son-in-law was right & basic Plod wrong. This could possibly be what was happening in the report above.
Agewise, the youngest age for tractor driving on the road is actually 16, but there are size limits involved which does rather preclude a 14 year old, except that I seem to recall being told that you could do it to cross a road if said road split the farm. Apparently, once 17, they can indeed drive a fully loaded 31T outfit on a Class B licence. And let's face it, some fresh faced 17 year olds can indeed look much younger than 17.
In respect of motorbike front number plates, yes, they were indeed known as slicers, however some bikes, I had one, had two front number plates, one on each side of the front mudguard whilst others had a single plate mounted across the front forks and facing forward.
Of course, there are motorists, touristy types, who faced with a large tractor driven by a camparitive youngster try to take advantage. My grandson was faced one such type who tried to claim that grandson had hit him with his big balloon tyres, that was until he was told that had the wheels been turning, they would have left circular marks on the car body, not the straight lines that indicated that the car driver had indeed tried to force his way past whilst grandson was stationaary.
Cheers,
Peter G. Shaw