A cheeky sleepover at an always-open shootin' hut in the North Pennines has pushed me up to 42x42.
More significantly, I reckon, I've filled the gap between Bollihope Common and Swinhope (high land between Teesdale and Weardale). I kinda thought it would be impossible, even though it's access land, as there are hardly any tracks, only one legit bridleway, and a dirty great quarry covering a big lump of it.
Actually, I did miss one tile, but it's the one with the legit bridleway through it. To get the rest, I had to scale stone walls and wriggle under fences (out and back), then all the rest. Tis done.