These produce blue berries that the birds love to eat. Maybe it was too cold for them to be poliinated properly this winter. Yes, the flowers will have little berries under them. All berries were once flowers of some sort.

Our mahonia has produced no berries at all this year... far too cold and the shrub was covered in snow so no chance of pollination.

Thanks for answers. I had another look between sleet showers. There are a few tiny berries lower down.