If you are considering walking this route yourself, please see my disclaimer. You may also like to see these notes about the maps and GPX files.
I turned right along the lane, soon passing Valley Farm (Valley End Farm on the OS map) on my right. Just before reaching a couple of cottages on the left, I took a footpath on that side that was soon following a hedgerow on my right, going fairly gently uphill. After a while the path went over a stile in the hedge and crossed some grass to a farm track, where it turned left and followed the track over the top of this small hill and down the other side. In the valley bottom it merged with a bridleway just before reaching a road. I turned right, following the road in the direction of Middle Assendon.
The lane through Bix Bottom
The path after I turned left from Bix Bottom
The path after it goes over a stile in the hedgerow
Further along the same path, after it joins a farm track
The road towards Middle Assendon, after I turned right
After a few hundred yards I came to a farm gate on the left where a footpath started, going sharply left and uphill across a sheep pasture to reach Paradise Wood (I saw a Buzzard here). The path continued fairly easily uphill through the wood - I was surprised to see some Nettle-leaved Bellflower still in flower here. Eventually the path turned right to reach a stile on the edge of the wood and then then rose more steeply beside a hedge on my left, levelling out after the hedge turned left. The next mile or so, heading north to Coxlease Farm, was quite delightful - it's one of my favourite paths in the Chilterns (though I usually walk it in the opposite direction). The path followed a farm track between a hedge on my left and a small embankment, with fine views along and across the Stonor valley down to my left. I saw another Buzzard along here, and also saw some Common Field Speedwell and Field Scabious.
The path to Paradise Wood
Paradise Wood
Paradise Wood
The path continuing to Coxlease Farm
The path continuing to Coxlease Farm
The path continuing to Coxlease Farm
The path continuing to Coxlease Farm
View along the Stonor valley
The path continuing to Coxlease Farm
View back from the path to Cowlease Farm