"They represented a lovely understated utilitarian aesthetic, which is why it is ridiculous that people are going out and buying new ones. I do not condone this and I think people should be reusing their old jam jars. All you have to do is soak them in hot water and peel off the label, so there is no excuse."

Researchers at Kantar Worldpanel, a consumer analyst, found that adult packed lunchboxes are coming back into fashion with 26 per cent more 25 to 35-year-olds choosing to take them to work last year compared with the year before.

The trend is driven in part by workers being inspired by celebrity chefs who are expanding into convenient lunchtime recipes as they strive to fill a gap in the market for packed lunches.

Instead of the traditional lunch box filled with "beige" sandwiches and snacks in plastic tubs, a rising number of workers are opting to take more elaborate lunches to work in sealable glass jars.

This allows them to pour hot water over noodles or vegetables, creating an instant hot meal which food critics have described as the "posh pot noodle".

The food bloggers Jasmine and Melissa Hemsley, known for their "clean living" cuisine, have been pioneers of the trend, and have concocted recipes for jarred meals designed for health-conscious workers to carry to work and which include ingredients such as kelp and quinoa.