It is usually forbidden for quoted companies to cash in on bloodthirsty conflicts fought by armed mercenaries in distant lands.

But for Kevin Rountree it’s just another day at the office. The low-profile accountant, who never gives interviews, runs fantasy figure seller Games Workshop which this week emerged as the sleeper success story of the UK’s bombed-out retail industry, thanks to the enduring success of its tabletop game franchise Warhammer.

The Nottingham retailer and model manufacturer was catapulted into the FTSE 250 after pulling off a battle plan that Roboute Guilliman – the avenging son of the Emperor of Mankind in sci-fi spinoff Warhammer 40,000 – would be proud of.

The shares have risen more than 160% in the past year, giving the company a market value of £770m, more than breakdown specialist AA – one of the companies booted outed of the 250 index in the reshuffle – and the retailers Card Factory and Jacamo owner N Brown. Its current share price of £22.95 compares with £5 two years ago.

“Games Workshop fans act very much like those of Lego, as almost a cult following,” says GlobalRetail analyst Zoe Mills. “It is not cheap however, with great craftsmanship in its range, this is a hobby consumers are willing to invest in. It appeals to an older demographic than Lego, with detailed painting involved in the process. This is not for young children.”

Games Workshop shuns the press but on its website 47-year-old Rountree, who has been with the company for 20 years, sets out a simple stall: “We make the best fantasy miniatures in the world and sell them globally at a profit and we intend to do this forever.”

Although it has more than 460 stores around the world, Games Workshop insists it is a manufacturer first with its factory in Lenton, Nottingham, producing more than 30m toy solders a year. One of its financial strengths is ownership of the Warhammer franchise and it defends this intellectual property vigorously. The Lenton complex is also home to Warhammer World, an events centre that pulls in visitors from all over the world.

Rather than just being places to buy model kits or pick up the latest copy of White Dwarf magazine, Games Workshop views its stores as recruiting grounds for people it describes as having “our particular hobby gene”.

Someone with that trait is Dimitri, who has just bought a £95 kit to build an imperial knight. With more than 220 parts to glue together, the model will take hours of work to complete but the prison officer is no stranger to the task as he owns a shed filled with thousands of miniatures.

Players collect forces of miniature plastic models, all with different stats and abilities, and use them to play out clashes on a tabletop battlefield. “It’s very strategic,” says Dimitri of Warhammer “40K”, which is his game of choice. “It’s 10-fold more complicated than chess.”

He adds: “I got into gaming as a kid but as an adult I enjoy reading the lore. If you think of Lord of the Rings and the universe created by three books imagine what you can do with 50.”

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In January Games Workshop announced record sales and profits for the first six months of a financial year that runs until the end of May. Sales were up more than 50% at £108.9m while profits more than doubled to £38.8m as its UK manufacturing base protected it from currency depreciation. Most of the growth is coming from outside the UK with international sales accounting for nearly 70% of turnover thanks to expansion into markets like Asia.

Games Workshop was founded more than 40 years ago by three school friends: John Peake, Ian Livingstone and Steve Jackson. The gaming fanatics shared a flat in west London where they started out selling handmade, classic wooden games before going on to open stores. Following a management buyout in the 90s the company listed on the stock exchange in 1994.

Games Workshop is better run now than in previous years, says Dimitri who spends £100 a month in its stores. “Before you could spend £200 and have an army but then it would stagnate for two years. Now there are new releases all the time and they have tapped into the love of lore.”

In the Warhammer shop on Tottenham Court Road, shoppers are greeted by a dramatic snowy battle scene featuring two model armies, dragons and all, advancing on either side of an imposing fortress. A display cabinet in the corner groups figurines by army with the shelves labelled destruction, chaos and death. Other shelves are replete with battlefield scenery props with esoteric names like ferratonic incinerator and promethium relay pipes.

Although the central London store has several employees, more than 360 of them have just one person to do everything. The company monitors the success of its shops carefully and if those with several staff dip into the red they are replaced with one man stores.

The shops have playtables where staff give lessons on strategy and painting techniques like shading so enthusiasts can create give their models the perfect finish. Staff are expected to be immersed in games lore as customers quiz them about the nuances of orcs, ogres and obliterators.

In a world where so much free time is spent online, tabletop gaming is refreshingly analogue although the company encourages fans to share pictures of their finished figures on Facebook and Instagram. Games are played between people in the same room in venues ranging from schools to the former Olympic stadium in Stratford, where in May hundreds will gather for a Warhammer 40,000 convention.

“If someone said I was sad for playing with toys I’d say ‘what do you do’?” says Dimitri, who now in his early 30s has dedicated two decades to marshalling his fantastical troops. “Go down the pub?”

• This article was amended on 5 March 2018. An earlier version misspelled Roboute Guilliman as Raboute Gulliman and included a reference to Warhammer 10K where 40K was meant.

