In the latest taste test from consumer champion Which? more than 70 caterpillar cakes from nine major supermarkets were put to the test. Each cake was tasted 75 times, and the results were surprising. Marks and Spencer's Colin the Caterpillar cake has been a favourite for more than 30 years; however, the cake was beaten by nearly every competitor, scoring 64%. Forty-four percent of the 75 tasters found the M&S cake "too dry" while 40% claimed the chocolate flavour wasn't strong enough. The cake was also the least healthy, with the highest levels of sugar (46.3g) and fat (21.3g) per 100g. At £9.50, Colin was also one of the most expensive.

The number one spot went to Waitrose's Cecil, which also received the prestigious Best Buy rating from Which?. The cake received a score of 78%, with most cake enthusiasts loving the thick chocolate shell and the sponge-to-buttercream ratio.

Cecil was also commended for staying remarkably moist.

Cecil is one of the more expensive caterpillar cakes on the market (£9.50), but he's also the largest specimen tested (744g), making him more cost-effective by weight than M&S and many of his cheaper rivals.

In joint second place, with a score of 73%, was the Co-op Party Time Charlie Caterpillar Cake, which was the priciest cake tested at £9.85. However, the cake impressed the tasters with its "spot on" chocolate flavour and rich buttercream that compensated for a slightly dry sponge.

Also in second place, with a score of 73%, was Sainsbury's Birthday and Celebration Wiggles the Caterpillar Cake, priced at £8.50. The cake looks remarkably similar to the famous M&S cake but without the M&S price tag. However, the tasters found the sponge wasn't as moist as they'd liked.

Aldi's Cuthbert the Caterpillar Cake, priced at £6.99, came in joint third place. Scoring 72%, the cake outperformed M&S and was commended for its "creamy" buttercream. However, just over a third of the panel found the sponge slightly dry.

Morrisons' Morris the Caterpillar, priced at £9, also scored 72% and also had the lowest sugar content and the best-rated buttercream texture of the entire test.

The panel noted the sponge was a bit dry, but praised its chocolate flavour, ranking it second overall. It's an excellent option for anyone who enjoys a rich, creamy filling.

Iceland's Lewis and Green Caterpillar Celebration Cake earned Which?'s Great Value endorsement at just £4.50. While most cakes were criticized for dry sponge, Iceland's offering stood out for its moistness, despite being the smallest tested at 530g and having a thinner chocolate shell.

In response to these results, M&S highlighted that Colin the Caterpillar was named the nation's best caterpillar cake in a March 2026 YouGov poll and boasts the highest chocolate content on the market. The company also stated that it regularly tests Colin cakes against competitors to maintain its standard for taste and quality.

An M&S spokesperson said: "Colin the Caterpillar is the UK's number 1 caterpillar cake - over a million are sold every year. He has been named the nation's best caterpillar cake in an independent YouGov poll.

"Made and finished by hand in the U.K. for over 35 years, it leads the market on quality and taste. It has the highest chocolate content on the market at 39.5%, with milk chocolate made from 31% cocoa solids and 100% Fairtrade cocoa.

"At M&S, blind taste testers regularly taste our products against the market to ensure we remain number one for taste and quality - this includes our Colin cakes, which consistently come first in taste tests."

Natalie Hitchins, Which? Head of Home Products and Services said: "For many of us, a caterpillar cake is the ultimate nostalgia trip, but our test shows that you shouldn't let brand fame dictate your birthday budget.

"While M&S created the category, rivals like Waitrose and even budget-friendly Iceland are now delivering a better slice of the action. Whether you're looking for the best taste or the best price, there are better options out there than the original Colin."

• Asda Letty The Caterpillar Cake - 68%, £9


• Lewis & Green Caterpillar Celebration Cake - 67%, £4.50


• Tesco Slinky Caterpillar Cake - 66%, £9


• M&S Colin The Caterpillar Cake - 64%, £9.50