Unfortunately, there’s been a mix-up with the lids to these yoghurts.
From the Food Standards Agency:
A limited quantity of Low Fat Summerfruit Yoghurt film lids have been incorrectly placed on Low Fat Dessert Style Yoghurts which are otherwise fully and correctly labelled. The Low Fat Dessert Style Yoghurts contain gluten and egg which makes the product a potential risk for people with a gluten intolerance or egg allergy.
These are the four-pack Low Fat Summerfruit Yoghurts, with a use by date of 17 January 2008. If you’ve got some, don’t eat them but take them back to the store for a refund.