It was time for a visit to the fictional county of Midsomer, which has a higher murder rate than even Inspector Morse’s Oxford – not least because of an impending meeting with my German sister-in-law, a long-time fan of both TV detective series.

We took the X8 bus from the tourist-filled city centre to the relatively quiet marketplace in Thame, which has featured on TV’s Midsomer Murders as the town of Causton. The wide high street is remarkable, with grand Regency mansions rammed in next to tightly-packed black-and-white timbered medieval buildings, and a ‘Middle Row’ framed by the town hall.

We didn’t see anyone who looked like a tourist, despite the beautiful setting – and the signs outside the museum offering Midsomer Murders tours and trails.

We walked past the higgledy-piggledy almshouses, now facing a quiet courtyard and a bizarrely-placed bandstand, next to the ancient grammar school buildings. Apparently the school was used as a dance-hall between the two world wars, and the bandstand was bought from Lord Rothschild’s house at Halton, near Aylesbury.

The church is also remarkable, more like a cathedral than a parish church, with unusual wood carvings and a magnificent alabaster effigy of Lady and Lord Williams, who founded the grammar school in 1559.

We wandered back to the marketplace, stopping for coffee at Rumsey’s chocolaterie to sample a Barnaby bun, created after the cafe featured in Midsomer Murders. Enough of TV detectives – we wanted some proper countryside, so we headed down an intriguing alleyway towards the Cuttle Brook nature reserve, a green lung connecting the town to its rural neighbours.

We followed the brook, a tributary of the River Thame with its source in the Chilterns, along a willow-lined path fringed with reeds and rosebay willow herb. Across the stream we could see signs of the ridge-and-furrow humps left by the medieval ploughs before the area was enclosed by large landowners.

We were soon on the Phoenix Trail, one of the most popular parts of the National Cycle Network, a millennium project by Sustrans to create safe traffic-free routes for novice cyclists. At weekends the route from Thame to Princes Risborough is busy with dog walkers and baby buggies as well as bicycles, but on the day of our walk it was fairly quiet.

We soon turned south on a bridleway which bypasses the tiny village of Moreton, crossing water meadows to join a track up Horsenden Hill, which gave us our first glimpse of the Chilterns, an unmistakable blue ridge in the distance. The track becomes Judd’s Lane as it nears Tetsworth, passing a building site where 39 new homes are going up – quite an increase for such a small village.

We crossed the A40, now a quiet side road since the M40 was built, to reach the Old Red Lion, which has comfortable seats opposite the cricket ground – a classic English view. The builders have obviously boosted trade at this pub, which doubles as a village shop and serves tea in proper pots.

Tearing ourselves away from the sofa, we restarted our walk on the Oxfordshire Way, which crosses the road here en route to its endpoint (or beginning) in Henley.

Like the Moreton water meadows, this path is muddy in winter, but after our dry summer it was easy-going as we briefly diverted from the Oxfordshire Way to enjoy a view of the Chilterns from the east side of Lobbersdown Hill. The Vale of Aylesbury is so flat that even a 100m hill gives extensive views, and we enjoyed our sandwiches while picking out landmarks from Combe Hill above Chequers to the Stokenchurch radio aerial and Christmas Common.

We were about to cross land owned by the Oxfordshire Golf Club, which incurred the wrath of ramblers by building its clubhouse across a major footpath. Both the Oxfordshire Way and other footpaths have since been officially diverted and, having walked the longer trail a few years earlier, we were keen to try a different right-of-way through the golf course.

On the map this looked as if it took a wonderfully varied route, but turned out to be a tarmac track through barren grassland around artificial lakes with not a living creature to be seen, apart from a handful of golfers. We left the golf course quickly, crossing the A329 to rejoin the Oxfordshire Way and enter the wildlife-rich woodland of Rycote Park.

The only problem here was the number of pheasants underfoot, but we were soon out of the wood and following a path fringed with a hedge planted only a few years previously. On our last visit we had seen bare plants, but now the hedge was fully grown – a colourful mixture of hawthorn, spindleberry and other native plants that would provide a winter-long feast for the pheasants’ higher-flying cousins.

The Oxfordshire Way enters another short wood and then walkers emerge to the splendid sight of Rycote Chapel, surviving witness to a grand Tudor palace that once stood nearby.

There’s no mystery here, because the Bodleian Library has created online access to the site’s history. You can read how Henry VIII visited Rycote Park on his honeymoon with his fifth wife, Katherine Howard, and why the palace also hosted Elizabeth I, James I and Charles I – accounting for the grand pews in the chapel.

The great house burned down in 1745. Although it was rebuilt, the impoverished owner, the Earl of Abingdon, soon cleared the site, selling every brick, in 1807.

The turret and some stable buildings that survived were converted into the present private house in the 1930s by Cecil Michaelis, who founded Rycotewood College (now a furniture-making department at City of Oxford College).

The next part of our walk, from Rycote to Albury and Tiddington, is one of the best stretches of the Oxfordshire Way, on the side of a gentle ridge above the Thame valley that gives views over to Long Crendon, Brill and Muswell Hill.

The bus stop opposite the Fox at Tiddington is a five-minute walk from the footpath, and we were soon enjoying a panoramic view of the countryside along the A40, from the front seats of a double-decker 280 to Oxford.

The Red Lion at Tetsworth serves breakfast, and food all day except Sunday, when food is served until 3.30pm and the pub closes at 5pm (call 01844 281274). Rycote Chapel is open April to September on Fridays, Saturdays and Sundays, 2-6pm, or by appointment on 01844 210210. Directions for the Oxfordshire Way from Tetsworth to Tiddington are available on oxfordshire.gov.uk