A trolley clever way to beat 5p plastic bag tax but at £17.99, it will take nearly 100 shopping trips before you save money 

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It's the eye-catching answer to the 5p plastic bag fee that will save you money – but only after you’ve made nearly a hundred shopping trips.

The brightly coloured bags are designed to slot into supermarket trolleys so shoppers can load up at the checkout before wheeling them out to the car.

The washable fabric and mesh bags are sold in four-packs – enough bags to contain a typical weekly shop – for £17.99. Buying four plastic bags under the new compulsory charge introduced this month would cost 20p, meaning it would take 90 shopping trips with the four-bag system before you start saving money.

These brightly coloured bags are designed to slot into supermarket trolleys so shoppers can load up at the checkout before wheeling them out to the car 

Sales of the Trolley Bags UK packs have soared from 200 a day six weeks ago to 2,000 a day. The bags come in vibrant colour combinations and in two sizes – to fit a standard trolley or the express, shallower version. They have plastic arms that spread over the trolley, allowing the shopper to organise items in separate compartments.

Joby Cronkshaw, managing director of Trolley Bags UK, said: ‘It’s been unbelievable. We launched a year ago and sales had been steady. But it picked up about ten weeks ago and I’ve had to increase our staff from five to 11. In the past two weeks, demand has been crazy.’

On Friday, the company apologised on its Facebook page for delays in deliveries of the bags caused by the surge in demand. But not all customers seemed to mind. One, Lynne Edwards, wrote: ‘Well worth the wait, don’t know what I ever did without mine.’

Fashion-conscious shoppers have also been snapping up £39 foldable tote bags by designer Lulu Guinness

A Tesco store, in Oldham, Greater Manchester, made the decision to security tag its baskets after a third were taken in a week. Meanwhile, stores in London tagged their plastic bags following the introduction of the charge

Mr Cronkshaw hopes to add freezer and bottle bags to the range. He added: ‘I’d also like to bring out different colours and patterned bags, but the challenge at present is getting the stock.’

Fashion-conscious shoppers have also been snapping up £39 foldable tote bags by designer Lulu Guinness. A spokesman said sales had increased 300 per cent in the past five weeks. Among the bestselling designs are bags called Polaroid Lips, Black Doll Face Luisa, Lucy Tape Face, Black and White Striped and Lulu Letters.

House of Fraser, Debenhams and John Lewis said it was too soon to report any impact of the bag fee, but a Lakeland spokesman said: ‘Four in five customers are not paying for carriers.’