The study would encompass sales of all product variants and rank brands according to the value of their sales.

For Coca-Cola, that would entail sales of its sugar-free and diet variants.

"Obviously Coca-Cola is an iconic brand and it's obvious a very, very popular brand here," said Maev Martin, editor of Checkout magazine, there are a lot of variants in the Coca-Cola family - so people are quite possibly opting for no sugar options, because that's a very big trend in the market."

"The variety of its product portfolio and the way it has responded to consumer trends, and also the fact that it's such an iconic, global brand, that's really what's kept it at the top for the past 20 years."

The soft drink company is one of five that has maintained its position from the previous year.

In 2023, the rankings of Lucozade (ranked 2nd), Tayto (3rd), Cadbury's Dairy Milk (4th), and Red Bull (8th) have all remained the same.

The Coca-Cola Company owns a share in Monster energy drinks, which ranked as the fifth best-selling brand.

Avonmore and Brennans, two Irish brands, came in sixth and seventh place, respectively.

Brand of chewing gum 7-Up dropped to 10th position in this survey while Extra moved up from 12th to 9th place from the previous year.