Nevine Mann's kitchen cupboards are stuffed with cans of beans and packets of spaghetti. Tubs of paracetamol, ibuprofen and Calpol bottles are crammed into plastic tubs. Under her stairs are stacks of tinned tuna, dried fruit, rice and couscous and cartons of long-life milk.

The roof of her home outside Redruth in Cornwall boasts newly installed solar panels, while her garden contains three vegetable patches and a 1,300-litre water tank. Her garden shed is filled with dog food.

Nevine, 36, and her husband Richard, 37, a web developer, are 'preppers', a term that evokes gun-toting, paranoid survivalists building bunkers in the middle of the US desert.

Nevine Man (left) with her daughter Paige aged 5 (right), at their home in Illogan, Cornwall

But the Manns aren't preparing for nuclear war or a zombie invasion. They're getting ready for an imminent reality – March 29, 2019, Brexit day, when Britain will quit the European Union. 'If, by then, we have a deal with the EU, then hopefully everyday life will carry on more or less as normal,' says Nevine, a former midwife, who cares for the couple's three children Oliver, 18, Ethan, 13, and Paige, five.

'But if we've failed to reach a deal the consequences could be scary: we just want to be ready for that.'

Extreme? Paranoid? Potty? Very possibly. But Nevine and Richard are just two of Britain's Brexit 'preppers', a fast-growing group stocking up on essentials to ensure they can live out the weeks if there's no deal when, without any customs agreements in place, established supply chains could break down.

Jen McEnhill (pictured) from London is also stock up and has been buying Brexit box supplies.

While Ministers dismiss such talk, alarm began in June after news was leaked that the Government had outlined different scenarios for a no-deal Brexit. The worst was dubbed 'Armageddon', with the port of Dover (where a third of all our food supplies arrive from Europe) grinding to a halt. Lorries might then be stuck for days on motorways waiting for import checks as their loads of fresh produce rot.

'The supermarkets in Cornwall and Scotland will run out of food within a couple of days, and hospitals will run out of medicines within two weeks,' said a Government source.

The boss of Amazon UK, Doug Gurr, also warned the then Brexit Secretary, Dominic Raab, that no deal could lead to civil unrest 'within days', leading Raab to confirm the Government was planning to stockpile food. For the first time since the end of rationing in the 1950s, it appointed a Minister responsible for food supplies.

Some of the stockpiled 'essential' items including honey, sweetcorn and tinned tomatoes

The Government is also considering cancelling all police leave in case of unrest and chartering ships to bring urgent food and medical supplies into ports that are less busy than Dover. The Army, meanwhile, is on standby to help distribute provisions.

'We'd been planning, initially, to have enough food to keep us going for two to three months,' says Nevine. 'But then the Government confessed that Dover might be running with 12 per cent to 25 per cent of its normal capacity for up to five to six months, so we went 'Oh! Let's aim for six months as a minimum', which we've more or less reached.'

Nevine is one of the more than 2,000 members of the Facebook group '48% Preppers', who are readying themselves for a no deal.

'Some are preparing themselves for a virtual apocalypse, while others are stocking up on foreign goods that may be in short supply, such as olive oil, but everybody thinks it's sensible to do something,' she says.

Nevine Mann, 36, and her 37-year-old husband Richard have been buying extra ingredients each time they go shopping

And as the clock ticks down on Brexit, it appears increasing numbers aren't willing to leave things to chance. According to the emergency supplies and survival equipment store Evaq8, in recent weeks sales for items such as water-purification systems and emergency food rations have risen by 103 per cent.

'We've had at least double the amount of normal orders, and a lot of them were stockpiling food,' says Zaid Almufti, the company's sales director. 'There's definitely a stigma attached to prepping but it's always good to have a plan B.'

Like many Brexit preppers, Nevine was braced for ridicule when she disclosed her plans to friends. 'Some do think we're absolutely barmy,' she admits. 'They ask, 'Is no-deal Brexit really going to be that much of a problem?'

'I say, 'Well, yes, potentially. We are planning for the worst although we are hoping for the best.' '

While the traditional image of a prepper is a hippy living in the countryside, Jen McEnhill, 36, is very much an urban professional. A project manager for an advertising agency, she lives alone in a flat in Stoke Newington, North London, and has been stockpiling food since the summer.

Dominic Raab (pictured above) has previously confirmed that the government was planning to stock pile food

'When I tell friends and family I have a Brexit box full of provisions in my living room – where they are out of sight so I'm not tempted to use them – they're like, 'What?' They think I'm prepping for the apocalypse. But some of my friends with young children agree it's a good idea and want to follow suit. A few years ago I'd have found the idea of stockpiling a bit nutty, but for the past five months, since it became clear there are no clear plans for coping with a no deal, I've been buying double amounts of food with a long-shelf life, such as pasta, as well as medicines such as antihistamines and a few treats – like nice vinegars. I'm also filling the freezer with vegetables.'

She now has enough to last about three months.

'People can't cope if the supermarkets are closed just for Christmas Day and we can't necessarily put our trust in the Government to solve this issue quickly, so it's best to look after ourselves,' Jen says.

Jo Elgarf, 42, who lives in South London with her husband and children Youssef, six, and twins Layla and Nora, four, has compelling reasons to fear the practicalities of a no-deal Brexit.

'This isn't about Remain or Leave, I'm a normal, everyday mum with little interest in politics and I'm not a panicky type,' she says. 'But I used to work for a big food company so I understand the supermarket supply chain and how it can be disrupted.

The amassed goods are enough to survive a no-deal Brexit for at least four months

'It only takes a couple of days' snow for shelves to empty. So over the past few months, I've been doing my shopping for next April now – stockpiling enough food, powdered milk and things like washing-up liquid to keep the family going for six weeks. I've also been buying compost to sow seeds in my tiny garden because fresh vegetables may be scarce for a while.'

But what Jo fears most is the one thing she can't prepare for. 'My biggest worry is for my daughter Nora: she has cerebral palsy and severe epilepsy and is prescribed lots of imported medicines I can't buy over the counter. If she doesn't take them, she can have uncontrollable seizures that could lead to sudden death. If I could store up those medicines in advance, I would, but that's not possible.

'I've sought reassurance her medication will be available after a no-deal Brexit, but received none. Not being able to help her is beyond worrying, I feel physically sick thinking about it.'

Back in Cornwall, Nevine and Richard have taken Brexit prepping a step further than adding to the weekly shop.

Having never been green-fingered, when they moved into their four-bedroom house this summer, the couple started tending a blackberry and raspberry patch to give them fruit in summer and are now growing vegetables, too, studying gardening books for guidance.

Having never been green-fingered, the family started tending a blackberry and raspberry patch to give them fruit in summer and are now growing vegetables

'Even the odd carrot or potato will be better than nothing,' says Nevine.

The couple have also prepared 'bug out boxes' – bags stocked with three days' worth of essentials that can be grabbed quickly in the event of a fast evacuation. They've also made it a priority to install solar panels in case of power cuts – a lot of our electricity is imported from France. 'We'd always intended to do it, but getting them up became a matter of urgency because a lot of equipment is imported and may not be so readily available after March,' she says.

'There's the same worry about water, as a lot of the chemicals used to purify our tap water come from Europe, but we have a big rain butt and the equipment to make its water drinkable cost less than £35.'

What's still of concern to the couple are items they can't stock up on in advance, such as petrol (you're allowed to store only 30 litres at home) and medicines, many of which are imported and have a short shelf life.

The Government has asked pharmaceutical companies to store six weeks' supply of medication, but what happens after that remains unclear.

'My 13-year-old has a severe grass allergy and takes prescription antihistamines – if he can't get those, then he can't leave the house for six months,' says Nevine, who takes medication herself for mild epilepsy.

She hopes to get a little extra of the family's medicines from her GP before the end of March and admits: 'At least our conditions aren't life-threatening. I have a friend whose child has cancer and is receiving chemotherapy where the drugs are very time-sensitive. If she can't get them, she doesn't stand a chance. It's desperately worrying.'

Retired police officer James Patrick is the author of a leaflet, Getting Ready Together, with advice for preparing for a no-deal Brexit.

While it covers subjects such as how to keep warm in a house with no central heating, he says there's no need to stockpile more than a week's supply of food because the delays predicted at the port of Dover for delivery lorries are for about five days.

'This is a case of having some candles as well as a torch, a battery-powered radio, perhaps a solar-powered phone-charger,' he says.

'You just need two cupboards of food and some extra toilet roll and coffee – because a lot of it comes through Germany – unless you fancy roasting acorns.'

On December 11, the Prime Minister's Brexit deal will be put to the vote in the House of Commons. Whether it is approved or rejected will be key in establishing the likelihood of a no-deal scenario in March.

Prime Minister Theresa May's deal will be put to the vote on December 11

As Nevine says: 'If Brexit passes smoothly, we'll just eat all the stuff we bought in time, and take any extra to a food bank.

'What we're doing is an insurance policy. We hope never to need it but peace of mind is there.'

It's easy to mock people like Nevine. But if Theresa May's plans are rejected, it's safe to say that the ranks of Brexit preppers will be swelling.