Running

I've used Walsh PB for years, up and down Box Hill, which is a mix of mud, chalk hills and gravel, along with some tarmac.

There's not a lot of cushioning, but they feel like slippers when I put them on.

Someone from my running club had some nice looking adidas ones with the boost foam which she liked. Not sure of the model, I'm afraid

I've been wearing INOV-8 shoes for ten years or so and having gone through a dozen or so pairs have only got good things to say about them. As ever, you'll get the best results if you can try a pair first, but for your needs I'd recommend Roclite or Trailtalon.

Saucony Peregrine definitely worth considering. I find them very comfy, excellent on trails, a little firm for my liking on tarmac but my feet are particularly niggle-sensitive. If I was after a road/trail shoe now I'd probably look at Hoka, e.g. Challenger ATR, mainly because I've got on so well with their road shoes, so if they can grip in the mud whilst offering that bit more cushioning that would be right up my street.

Have moved recently and my regular route now has about 2/3 grass and trails to 1/3 road

Grass as in flat park grass? If so (and not rough, muddy, undulating trail surfaces) then a road shoe may suffice. I had a pair of saucony freedoms that were "ok" on the road but were perfect for regents park and hampstead heath "off road" tracks. Minimal drop and wide meant they were stable, and the cushioning was enough to absorb pebbles and the like. They'd have no traction in actual mud, and there's no rock plate or the like, but on grass and sandy trails none of that is actually needed

Its all a compromise, but I found them a better compromise than a trail shoe on the road.

That all said, if you do want a cushioned trail shoe, then the peregrine is worth a look