From Oxford heading north, you can go in three directions by rail - turn left for Worcester, go straight ahead for Banbury and the North, and turn right on a (currently) truncated service to Bicester.
I was in Cambridge this week, and travelled back last night - by road, as I had major luggage with me, and a diversion after Milton Keynes brought me to a sign that said "Verney Junction" - somewhere I had heard of and I knew that bu following the line of the railway I would get (via there) to Bicester and Oxford.
Verney Junction - the sign still says "Stop and phone the signalman if you have a large or slow vehicle" but there's not been a train for years.
Underneath the undergrowth at Verney Junction - Track still in place
The old Bletchley bound platform
Verney Junction is a small village - a railway community now without the railway
Middle Claydon
Middle Claydon
From Calvert (where the line meets the truncated old Great Central line), there is a line which appears to be in use and good condition - freight?
Near Marsh Gibbon
Launton
Although sections of the line look pretty depressing and the countryside is rural in the area I was passing through, this route could offer a fantastic opportunity to provide crosscountry connections between major towns, and a superb connectional service that meant that many journeys which currently involve goion in and out of London would be much shorter.
If you doubt whether people want an "orbital" / London avoiding route, have a look at just how busy the M25 has become.