"It is a great concern for us, " said Wexford blackcurrant grower Des Jeffares, whose business has been in the family since his grandfather's time. "Blackcurrants need a good, cold winter and what is described as a lot of chill hours to do well, and if the winter isn't cold enough, the entire crop is in danger. It can lead to an uneven flowering time, which means lots of the fruit is overripe by the time it comes to harvest."

The past few years have seen a lot of mild winters, with last winter being one of the mildest to date.

"We were 400 chill hours short, which is a lot, " said Jeffares. "Then we had a very serious frost in May and that did a lot of damage."

Scientists in Scotland are working to replace the typical Irish blackcurrant with a hardier breed that is more amenable to a mild climate, and it is hoped that this will be able to save blackcurrant crops.

"We just have to hope that these breeds can replace ours sooner rather than later, " said Jeffares, who is best known for his appearance in the Ribena ad. "In the meantime, I'm just hoping that it's just a bad cycle and not really a change in climate."