Maybe that the berries have been collected already, or eaten by various creatures when you notice them. If you notice their flowers, then its possible they're not pollinated and don't form berries, or they don't flower properly because of cutting or interference of some kind. They usually flower and fruit profusely without any trouble, don't need a particular pollinator. Unless you've a distinct shortage of bees and other insects there.

Winter browsing by deer--common in northern Arizona, but I don't know about Ireland--can cut off the flower buds before they open. Excessive shade, or nutrient deficiencies, among second-growth forest can also prevent blooming.

thanks for your replies.
gerry