Science labs, parks, health centres and community arts hubs, lecture halls, bowling alleys and even a submarine training centre.

Former Debenhams stores across the UK are being reinvented with a dizzying array of new uses as councils and landlords battle to fill millions of square feet of space left empty after the demise of the department store chain in May 2021.

The Debenhams name continues online under new owners but – three years after the department store chain left the high street – more than half of the former stores remain empty or are in the process of being redeveloped, according to research by Local Data Company for the Guardian.

Only a third of the enormous sites, many of which are the keystone of local high streets, are now occupied by retailers, although a further 7% have a new occupier lined up according to the LDC research.

Cities and towns including Basingstoke, Exeter, Middlesbrough, Nottingham, Sheffield and Swansea have yet to fill the large gap on their high streets or have not confirmed plans for the site, with several of those places also having lost a House of Fraser or a John Lewis as well.

Only a handful of the former Debenhams shops have become new department stores, with independents Bobby’s and Bradbeers opening in Bournemouth and Salisbury respectively.

Marks & Spencer and the owner of House of Fraser, Frasers Group, have both filled a number of former Debenhams stores. Frasers has picked from its huge array of retail brands, from Sports Direct to luxury casual wear purveyor Flannels, Everlast gyms and its Frasers mini department store format to fill the spaces.

Next and Primark have also taken large chunks of space while, last November, Ikea’s parent group bought the Brighton mall that previously housed Debenhams with a view to repeating its successful reinvention of the Kings Mall in Hammersmith in west London, where it also filled a defunct Debenhams.

But with evidence that 52% of UK destinations have too much retail space, according to consultancy CACI, the majority of Debenhams sites are unlikely to be filled by more shops.

Instead there are plans to turn former Debenhams into science labs in Oxford and Cambridge, a park in Cardiff, health centres in Basildon, Bangor and Carmarthen and lecture halls in Gloucester.

Perhaps most unlikely, aerospace and defence group BAE Systems has bought the Debenhams in Barrow with a plan to build a training centre for submarine engineers.

“It was a blow,” admits Michelle McPhee, the town centre manager for Middlesbrough, as she contemplates the struggle to fill Debenhams, an empty House of Fraser that sits opposite in the centre of town and a more recently closed Marks & Spencer and Wilko.

“But it wasn’t a shock. Department stores were closing as retail is changing and because of Covid. We were quite prepared.”

Middlesbrough is one of the hardest hit town centres in the country from the mass closure of department stores, many of which continue to lie empty as few retailers continue to want the kind of space they occupied.

While the town has 1.4m sq ft of space over just four retailers to fill, there is a will and determination not just to put any tenant in that space.

The council has set a strategy with entertainment, retail and leisure zones within the town centre and is trying to build a mix of attractions to entice footfall back.

Its Debenhams building, which was finally bought from administrators by a local property developer in January, and House of Fraser, which is now owned by the Tees Valley Combined Authority’s Middlesbrough Development Corporation, are likely to be redeveloped for a mix of uses – with retail on the ground floor and offices, a hotel or another form of accommodation above.

“Anyone who comes into town can see it is difficult. But if you just think the town centre is over, you are never going to recover from that,” says Chris Cooke, the mayor of Middlesbrough.

“What we didn’t do was abandon it and clear everything for hotels. It takes much more to make a proper, well thought out strategy.”

Mark Robinson, chair of the government-backed High Streets Task Force and co-founder of developer Ellandi, says he believes some Debenhams sites are “going to be empty for quite some time” as there is little demand for new retail or leisure and converting to alternative uses generally requires public funding.

He said it was not surprising that it had been difficult to fill Debenhams stores because many of the sites are fairly modern buildings that are “riddled with asbestos”, while the group had expanded rapidly under its private equity owners into buildings that had lengthy leases and unaffordable rents.

Finding an alternative use for these sites is also trickier than it first seemed.

While some owners or local authorities had planned to convert department store sites into much-needed homes, the increased cost of construction and finance mean the economics no longer stacks up in many places. The chunky shape of department stores also means they are not easy to adapt for residential because it is hard to get light into the centre of the building.

New building regulations, which demand certain levels of energy efficiency, and delays in the planning system across the country, only add to the complexity and cost of reinventing the buildings, according to Jonathan Wallace at planning consultancy Lichfields, which has advised on a number of department store reinventions.

He says many local authorities are keen to see these key buildings redeveloped but can face a battle with owners who do not wish to take a cut in the value of their asset or accept that no major retailer is going to take their site.

In areas including Bristol, Leicester and Northampton, Debenhams sites are being razed to make way for flats or student accommodation – but that has caused local controversy in some cases because of fears of overbearing high-rises in the city centre.

“There are a lot of ideas out there but it takes a long time to go from an idea to a scheme and then get planning and come out the other side,” Wallace says.

Robinson says the way government money is allotted to town centre development needs a complete overhaul so that local decision makers can direct funds to where it is really needed in order to speed up redevelopment.

“We have got to stop the Mad Max-style competition for funds and it has got to be devolved. Information is always more local than Whitehall,” he says.

Middlesbrough’s mayor Cooke agrees that the government funding system needs an overhaul so that it does not just focus on large capital sums for buildings or renovations but bears in mind the need for ongoing revenue to keep a project running.

He says, for example, that the town could have used £20m in levelling up funds to build “a lovely brand new library but we wouldn’t be able to staff it”.

“My major plea to government is that they absolutely focus not on just giving money to have a big number but with a revenue stream attached so we can deliver the projects,” he adds.

Despite the difficulties, he insists that Middlesbrough’s plan is working. The council has bought a local shopping mall and changed it into a more leisure-based centre and is hoping to put a health and community centre into another mall.

It filled its once-empty BHS with upmarket chain Flannels, attracted more independents and new arrivals include a Wendy’s burger bar, and a soft play centre is set to occupy the former Wilko.

Wallace from Lichfields says this kind of mix will be the way forward for many towns: “In the 1950s town centres had much more of a mix of uses. Then retail came along in the 80s and dominated it by the 90s. From a historical perspective, town centres are going back to where they were 70 or 80 years ago.”

“We are giving people another reason to come to town – wellbeing, leisure, to work and to live, to visit and stay,” says McPhee.

“It’s about education. A lot of local people are like – ‘It’s not got a Debenhams and an M&S’, but most towns don’t have that now.”