Tubs of luxury brand Haagen-Dazs are now 40ml smaller than they used to be but cost an extra £1.15. And a 500ml tub of Ben and Jerry’s once priced at £4 is now 35ml smaller and costs £5.

The new range, Potz, will be the first mass market confectionery brands to compete with premium mini tub ranges by Green & Blacks and Haagen Das. Nestle claims the range will be less than three times ...