After many years of battling with rabbits in every conceivable way I sorted my problem. But it wasn't easy or cheap.
60cm small cell wire mesh turned outwards in a L-shape with the foot of the L buried just under the grass, then more wire mesh above. Needs to be a minimum height of about 1.2 preferably a bit higher otherwise they will climb it. Doing it in two separate sections means you can follow the lie of the land at the bottom, then normal fence at the top
Then ruthlessly ferreted everything out and filled in all the holes so it was obvious if anything was still there.
Rabbit free garden for around 8 years now. What a relief
Did it about Im high in total at first. Walked across the garden with the dog. Rabbit at bottom, and as we approached it casually climbed the fence and disappeared. I was gobsmacked. Had to go all round again with more wire