Riding A Dirt Bike Down A Grassy Verge

[V8RX7]

IIRC you can't ride a none roadworthy bike on the verge as it's classed as the road

So what happens if a roadworthy motor bike is riding down the grassy verge ?

I ask as I saw someone riding on both the road and verge (having fun on a dirt bike at circa 50mph) and wondered what if anything they would be charged with ?

DWDCA ?

[Terzo123]

Sect 34 of the Road Traffic Act