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 followed the drive towards the farm and continued through the farmyard (where the Chiltern Way went right, towards Hailey). I carried straight on, now on a 'restricted byway' which curved right following the edge of a wood on my right. It then turned left, and followed an old hedge on my left gradually uphill towards Mongewell Woods. As I approached the woods, I stopped to admire the views, looking right towards the Berkshire Downs on the over side of the Thames Valley, and back towards the Oxfordshire Plain.
The drive to Woodhouse Farm
The byway from Woodhouse Farm to Mongewell Woods
The byway from Woodhouse Farm to Mongewell Woods
The byway from Woodhouse Farm to Mongewell Woods
View across the Thames Valley towards the Berkshire Downs, from the byway from Woodhouse Farm to Mongewell Woods
The restricted byway continued fairly gently uphill through Mongewell Woods - soon after I entered the woods, I had six cyclists pass me on their mountain bikes. It was uphill for about a third of a mile, then there was several hundred yards through the woods that was fairly flat. Shortly after leaving the woods I passed Upper House Farm (a very attractive old timber-frame building) and a little further on the byway became a lane (though I only know this from the OS map!). I carried on down the lane for another half mile to reach it's end at a minor road.
Mongewell Woods
Mongewell Woods
Mongewell Woods
The lane from Mongewell Woods, passing Upper House Farm
The lane from Mongewell Woods
I crossed over and continued down Whitcalls Lane. After a while this changed into another restricted byway, but again the change was imperceptible. Further on I passed the grand Oakingham House on my right - it looks Georgian or even earlier, but is in fact a modern house. The byway then continued between a wooden fence and a hedge on my right.
The start of Whitcalls Lane
Whitcalls Lane
The byway going southeast from Oakingham House