As the nation prepares to eat choc till they drop, we can lift the lid on the riddle of why your favourite Quality Street sweet plays so hard to get.

A study found that out of 67 sweets in a tin, only four were Green Triangles, but a sickening nine were Strawberry Delights.

And the thorny issue of why the Signature Truffle is a rare treat in Cadbury Roses is explained by it being outnumbered, nine to four, by Caramels.

After a poll to find the favourite sweets in Celebrations, Quality Street, Heroes and Roses, researchers at iProspect sorted almost 1,300 individual chocs.

Spokesman Shaun Hill revealed: “All the varieties rated in the top tier by our survey are among some of the less common chocolates in each tin.”

Nestle said it had responded to Quality Street fans and “switched up the ratios in each assortment so the mix of chocolate sweets has gone from 35% to 46%”.

Cadbury said Heroes and Roses were “regularly reviewed”, while Mars Wrigley said there was no “need to squabble” as all the Celebrations were “delicious”.