Many thanks to Simon (@woodbee69) for submitting this route.
A perfect cross-country ride from London into Wales using the A40 and A48 via Gloucester, totally avoiding motorways!
The route starts in Brentford, West London outside Griffin Park, the home of Brentford FC, and after a brief ride on the north circular, just pick up the A40 towards High Wycombe and stick with it through Headington on the outskirts of Oxford.
Stay on the A40 going past Witney and if you're lucky you may see aircraft flying overhead going in or out of RAF Brize Norton. As you get to Shipton Oliffe turn left on the A436 to Ullenwood and take in the wonderful views (but be careful, the road has been recently resurfaced so it may still be slippery).
Pick up the A417 for the short distance into Gloucester then head back on to the A40 if you want to avoid the city centre. Riding down the A48 following the river Severn takes you through some nice villages, memorably Blakeney with a twisty down hill, then as you arrive in Chepstow there's a pub and lodge with good food as well as Chepstow Castle.
With more time and some good weather I'd like to venture further into Wales next time.