A dark canopy above me spider-like: it’ s the first time I’ve slept in a four-poster bed. It’s an Indian four-poster: ruched fabric with a pattern of elephant and rider, carved headboard, and little elephant tables round the huge room. Through the tall windows the lawns spread around, and below is the curved glass canopy stretching the depth of the house. The Old Rectory in Dorset, built in 1730, with the wings added in 1814, was reputed to be the largest and one of the most beautiful rectories in England.

This is a Country House Weekend (but without servants – it’s all upstairs). An elegant wooden staircase spirals up the middle of the house, and the landings lead off to rooms beyond rooms – eleven bedrooms, bathrooms with roll-top baths (and all modern conveniences). In the 80’s – 1980’s – it was run by its owner as a small art school and an artists’ and writers’ retreat, and there are paintings and scuptures everywhere.

The house is a real character: exquisite and rather precious on the website, it feels lived in, and comfortable. Through the front door, through another door, now, left/right? past the Elizabeth Frink print, the waist-high metal jar, a limbless plaster torso, left into the huge living room with a grand piano, big fireplace: it’s an achievement to have found this room. Friends arriving late wouldn’t know the house was inhabited save for the piles of boots in the hall.

The treasure hunt: there’s scurrying up and down the stairs, people bumping into each other, or trailing through the rooms, lost and suspicious. As the organiser, I’m enjoying watching, and I think I’m pretty smart with my clues. Not that smart, though: it’s won by a team who jumped ten clues and found the treasure – a golden box of Bonne Bouche truffles – nestling on the bottom A strings of the piano (clue: ‘How Grand A Bottom Sounds!’) by chance.

After a hugely muddy walk to the sea, I lie in the big bath on the top floor: light off, I watch the silhouette of Colmers Hill’s pines against the darkening sky. I’m sure Thomas Hardy did, too.