A study timed 300 customers in and out of the supermarket and then quizzed them about how they felt as they shopped, what they smelled and whether they’d bought more or less than planned.

No scent was used in the first week, then in the second week a faint aroma of artificial melon was diffused into the food hall and checkout areas.

In the final week, the odour was made more intense, by the researchers from the Netherlands and Australia.

Melon was selected because it was judged to be universally popular, appropriate for the surroundings and easy to synthesise.

The evidence, published in the Journal of Retailing and Consumer Services, showed that the stronger the scent was, the longer customers stayed in the shop.