Many publishers would sell their grandmothers to be as successful as Shire Books. With titles like Medieval Wall Paintings and Tea and Tea Making, it has proved that people will still buy books, if they are interested enough in the content.

Famous admirers include TV gardener Alan Titchmarsh, who says: “Shire books tackle subjects that others fail to notice. Whether they are on gipsy caravans, horse brasses or heraldry, I simply love them.”

Founded in 1962 by John Rotheroe, Shire produces affordable non-fiction paperbacks that “reflect the interests and passions of ordinary people”, with hobbies from amateur archaeology and horse-drawn farm machinery to silver collecting.

With more than 1,000 titles under its belt, bestsellers include Timber-framed Buildings and Hallmarks on English Silver, both with more than 200,000 sales. Bottles and Bottle Collecting, a niche subject if ever there was one, has sold more than 150,000 copies.

Publisher Nick Wright, who took over when Mr Rotheroe retired and sold Shire to Oxford-based Osprey, said: "One of the reasons I enjoy Shire is its enormous range."

Mr Wright's hobbies are old cars, classical music and antiques, particularly clocks. He said: “I am the ideal Shire reader, but I had never bought a Shire book. I would look at them and put them down without buying, because they were extremely general and not attractive enough. That is what I wanted to change.”

Shire moved from its 17th-century headquarters in Princes Risborough after being bought by Cumnor Hill-based Osprey.

Founded as a niche publisher of military history, Osprey has expanded into other "enthusiasts" areas, having used a major refinancing from private equity company Alcuin Capital Partners — now majority owner — to buy Dorset-based British Wildlife Publishing and Old House Books & Maps.

One of Mr Wright's biggest successes has been the Old House replica of Bradshaw's Handbook, reissued in 2012 with impeccable timing. First published in 1863, it catapulted into the top ten UK Amazon sales list, with 150,000 replica copies sold, after being featured on Great British Railway Journeys, presented on BBC2 by former Tory politician Michael Portillo.

Mr Wright said: "It was copied very carefully, page by page, by someone who normally works for the Bodleian."

With a new Railway Journeys series on TV this year, he is expecting the continental edition of Bradshaw's to be another bestseller.

Shire’s first publication, Discovering East Suffolk, was a 24-page guide to the county, with five motoring routes and a gazetteer of towns and villages. From the start, it did not rely on bookshop sales, but was given free to visitors via coach operators, churches and tourist information points, and funded by adverts.

The book was a great success and many of the free copies were resold, so future editions went on sale without the adverts — but not just in shops. By the 1980s Shire books could be found in museums, country houses and other visitor attractions up and down the country. Mr Wright said: "One of the strengths of Shire is that it has such a strong representation in non-bookshop outlets. We do sell a lot in bookshops, but we have many museums and gift shops.

“Our biggest customers are museums and our biggest single outlet is the British Library, with the Imperial War Museum and the London Transport Museum next.

"Our health is governed by the health of the tourist industry, so Shire is affected more by the weather than by Kindle, which is not something you can say about the rest of the publishing industry.

“We are dealing with people who are keen to have our books,” he added.

Within a few years of being founded, Shire had branched out from gazeteers into other topics rarely, if ever, covered elsewhere — ice houses, early railways, classic MGs, thimbles, the slave trade, British film studios and the history of duelling.

Topics change as the readership ages. “Nostalgia is the single driving reason why people buy our books. We are more interested in the 1950s and 1960s now. Years ago it was all about Edwardian and Victorian life, because that was what people remembered.

“Of course, with Downton Abbey there is a new interest in those eras. In order to be successful you have to keep abreast with the things that are interesting people.”

He is keen to keep older books in print if possible, citing Dairying Bygones as a subject of declining interest, without enough buyers to justify updating in full colour.

“You will not get more sales by putting in more colour, but it is still selling and people are pleased that we can provide it, because there is no other book on that.”

With more than five million copies sold, Shire books are now being relaunched in new jackets by designer Peter Ashley.

One of the first in the new format is Medieval Wall Paintings, by West Oxfordshire author Roger Rosewell. The slim volume will take its place on the sales spinner with Witches and Witchcraft, Spas and Spa Visiting and Garden Gnomes.

Who knows what will be the next bestseller?