It's not a 3 wheel one, but I did google best all terrain pushchair and this one was very highly rated! I wanted four wheels. Not sure I'd have chosen this one if I'd been able to visit actual shops when I needed to buy as it is very heavy and quite bulky when folded, but it's done a good job on the few off road walks I've done.
Solid wheels so no punctures and it lies flat so it was fine like this from birth and I can lie him down flat when Jasper is sleep. It'll turn around to front facing when he's a bit older too.
Looking shiny when I took this photo as I'd hosed all the mud off it the day before!