Never raced on grass before. Is there any tyre make/type which is a big advantage on grass?

Dry grass or wet grass will dictate what’s best.
I’d want something light with a good edge though.

He’s the expert.

Still creepy.

Aye, one of the semi slicks with decent bitey side knobs.

Wet Scream with the centre mobs cut down – mibbie

Did a mates race dual slalom down a shallow gradient grassy field recently and Wet Scream is the answer. Even on a very flat gradient and with all that weight to wind up, the grip outweighs the heft.
Needs to be paired with something spiky out back too, or you’ll really notice the disparity in grip and end up doing lots of power oversteer…

Malverns like OP?

Something with a decent edge like others have said I reckon. There’s a local DH race here that has off-camber grassy bits and I found that the Conti Baron/Kaiser mix worked well enough for me. Not the lightest but they grip well on the sketchy bits.

Many years ago, specialized did some dedicated slalom tyres. Basically a 1.9″ dh mud tyre if I remember correctly… There may be some somewhere…
EDIT- evil twin slalom