As long as I can remember, I've been using the M40 from Oxford to London. The main geographical feature en route is what I call the "Chilterns Gap". This is where the motorway cuts a vicious trench through them thar hills in a feat of engineering that looks as impressive as the Chunnel project. Ever since I was a kid, this cut-through has been of particular significance to me. As a boy, driving through it spelt dread as it meant that I was only 20 minutes away from being incarcerated in my prep school for another term. As my parents' car slipped down into the valley – back to prison, back to hell – my spirits would sink. I'm never sending my kids to boarding school.

Nowadays, things are a bit better – driving through the Gap means that I've broken the back of my drive from London and I'm halfway home. As you drive through towards Oxford, there is a huge ridge that runs parallel to the motorway which has always seemed to promise a staggering view. I've always wanted to just turn off and find the way to the top of that ridge. For the past seven years, I've driven by and never done anything about my little urge. Then, a week ago, I went to record an item on Christmas trees for my Five Live Christmas special show. I was picked up in London and driven ... to the Gap. Just before we entered it, we turned off for Stokenchurch and visited a Christmas tree farm. This was my chance.

On the way back I pleaded with my production team to help me find the ridge. So, for half an hour or so, we drove down tiny lanes until I finally saw a sign for a nature reserve/viewpoint. This had to be it. We drove to the end of the little road and found a tiny car park. My team had considerably less interest than me in climbing above a motorway, so they stood around and smoked cigarettes while I went off exploring.

I wandered through a thick wood until I eventually found a footpath that took me up on to the hallowed ridge. I summitted after 10 minutes and it was magnificent. All I could have hoped for. Far in the distance were the smoking chimneys of Didcot power station. Just to my right, nestled between the Thames and the Cherwell rivers, were the dreaming spires of Oxford. Right below me snaked the M40 with hundreds of little ant-like cars busy fetching their occupants back from boarding school and heading home.

The roar of the traffic was intense, and yet there was a strange stillness to the scene. A lone sheep ambled up beside me and we both savoured the moment. Above us three huge kestrels swooped gracefully about in the thermals. I'd always noticed an abundance of these birds above the Gap and the owner of the Christmas tree farm had explained why. The billionaire John Paul Getty has a huge country house nearby and his estate introduced a pair of the birds to the area. Since then they have bred like... well, kestrels. So here I was sitting high above the M40 being strafed by a squadron of John Paul Getty's birds.

This was how I imagined having a shattering nervous breakdown. Park the car in the middle of the motorway, get out, strip naked, fold all my clothes into a neat pile at the side of the road and then run up the hill starkers shouting nonsensical rubbish about "them" coming to get me. With my sheep friend as a lone witness, I promised myself that I'd do this one day.

I took one final look and then plodded back towards my bemused but patient production team. They appeared completely uninterested in my spiritual experience and we drove back to London to interview Father Christmas. Ho-hum.