Leave the M4 at Junction 8/9, and take the turning for the A404(M) northwards. The A404(M) becomes the A404 after the A4 exit. Take the next exit for the A4130 towards Henley, and follow this all the way to Henley.
(NOTE: the alternative route if you would prefer more motorway is to follow the A404 all the way past Marlow, and join the M40 Northbound at the Handy Cross interchange, then follow the directions on the London/M40 page - if you are in a hurry, that's the way I'd go! It's longer but quicker!)
Once you reach Henley, go across the bridge, and past the first set of lights at the end of the bridge, and straight on up Hart Street. Turn right at the next lights onto Bell Street, towards Wallingford (the first right turn you can take - stay on the A4130) Follow this road past the shops, and out towards the roundabout. Go straight over the first roundabout, and bear left at the second, still following the A4130.
Follow the A4130 out of Henley and up the hill until you reach another roundabout. Go straight over towards Nettlebed. After a hundred yards, there is a turn on the right onto the B40, signposted towards Watlington. Follow the B480 into Watlington. At the foot of the hill, follow the road round to the left along Brook Street, go past the B4009 turn (Couching Street), and take the third right turn after Couching Street onto the B480, signposted for Cuxham & Stadhampton. CAUTION - this turn is easy to miss! NB - on some satellite navigation systems, there is a roundabout marked at this point. Whilst there IS a small triangular area, it is not a real roundabout!
After 200 yards, you will come to another roundabout. Go straight over, and follow the road through Cuxham, and on towards Stadhampton. This road has a number of sharp bends, so please be careful. Eventually, you will come to a long straight stretch of road, which leads to Chalgrove.
Turn left at the signpost into Chalgrove. Follow the road around to the right, and continue along the High Street. The Red Lion is on your right, opposite the village green. There is parking between the Post Office and The Red Lion adjacent to the Chalgrove Brook, or on the High Street itself.