Looks to be deep in the bushes alongside the unnamed road that connects Kidlington Road (to Islip), the sliproad exiting the A34 Southbound, and Bicester Road (in Kidlington).
The nearest road is about 10 minutes cycle from my (Dan Q) house, so I plan to zip out there either overnight (perhaps aiming for a Midnight Geohash?) or early in the morning. If you happen to plan to hit this hashpoint too, though, let me know and I can try to synchronise plans (but I ought to be spending the day studying, so I might not be able to!).
At 2018-08-03 23:02 (BST – local time) I started packing a bag and set out to the hashpoint. Suddenly it didn’t seem like such a good idea as it had in the warm sunlight, earlier: a dark and moonless night isn’t the best time to be cycling along unlit roads. But fully-equipped with lights and supplies, I set out nonetheless. I’d left longer than I needed and had about a quarter of an hour sitting by the side of the road before midnight came and I was able to visit the hashpoint (thereby gaining my Midnight Achievement).