‘Peter and I both had a little experience of hands-on restoration. In fact, our eyes met over a tub of limewash, half-way up a scaffolding tower, while working on a mutual friend’s Jacobean house,’ writes Judy Corbett in Castles in the Air. This book is a charming account of a young couple’s extraordinary five-year restoration of Gwydir Castle, a magical Welsh house near Llanrwst in the Conwy Valley. Love kindling over the limewash was surely a good thing because they have needed lots of both in tackling the much misused and abused castle.

This is a personal account, written very much in the first person, and there are moments of whimsy and romantic reverie which make you wonder whether they can really have been serious about the task. But serious they certainly were – and have been. Gwydir ceased to be a family seat in the 1920s, and was ill-restored in the 1940s by a Mr Clegg, who kept it standing but stripped plaster off walls and created bogus faux-medieval interiors that have had to be nursed back to reality.

By the 1990s, the overall fabric was in dire condition. When Judy and her soon-to-be husband Peter bought it in 1994 – for approximately the cost of a terraced house in Clapham at the time – it was owned by a psychiatrist who had plans for it. Some would have said they needed a psychiatrist rather than a castle.

The pace of the book really takes off when Miss Corbett, and her architectural historian husband Peter Welford, start plunging their hands into those tubs. Highly amusing accounts begin to roll off her pen: of discovering their sitting tenants; of recruiting the necessary builders; their own devotion to the castle (as if it were a person); their physical work on the building, odd incidents such as unearthing skeletons; and their, at times wearing, living conditions (on their first night, they lie on bubble wrap reading a civil-war account of the castle; on other nights we find them eating baked beans and drinking whisky against the cold). Then there are all the comedies of country-house life: opening to the public, dealing with film crews, bed-and-breakfast guests and wedding functions, as well as the best first-hand ghost story I have read in years.

The real thrill of the book is their discovery of a 1921 sale catalogue which proved that an early-17th-century carved room had not perished in a fire but had been sold from the house to Randolph Hearst. They trace it and find that it had never even been taken out of its crates. Through all sorts of convolutions – including a visit from an urbane New York museum curator, who can barely stand the primitive and cold conditions (much improved since) – they get this splendid room back in place.

This triggers a visit from the Prince of Wales, which is almost the topping on a rich cake (his shoes stick to the newly varnished floor and bed-and-breakfast guests arrive too early and shout up the stairs during a harp recital being given in his honour). One Christmas Eve, they get up at 5am to limewash the walls of a bedroom for a bed-and-breakfast guest who forgets to turn up. Later the same day they attend Midnight Mass in Llanrwst, where ‘as we were taking communion . . . I couldn’t help noticing that we smelt exactly like the old hassocks we were kneeling upon… basically how you’d smell if you’d been locked in a crypt for twelve years’.

Ah, but what a crypt.

Castles in the Air