Is this the legal or not?

Just shown this picture to a tyre fitter and he said it’s perfectly legal those little grooves are called stypes or something similar and although they help with grip they don’t need to be there.

Another interesting fact he mentioned after I pointed out the tyres on a decker I had today was that if you have twin tyres and one of them is completely treadless as long as the other has 100% coverage it’s all legal which surprised me.