Prunus spinosa possibly

Yep. In the top shot you can even see the characteristic spiny spur shoots.

Many thanks for the help. It did not occured to me to cut it open. In fact I thought it was Vaccinium because one of the fruits (the one with dark blue) seems like to have the carachteristic opening of the billbery. Now, on seeing with care, it was a damage to the fruit. The other fruits (colour green) seem much like prunes. I was in a rush, trekking and kind of took two quick pictures as I grow/collect fruit trees/shrubs for a hobby. @floral_uk, the fruit has a diameter of around 50 milimeters (half centimeter). The shrub is very small, around 50 cm high if so much. Does the Prunus spinosa can be eaten fresh and/or processed into jam?

50mm is right for Sloes. Google 'Sloe recipes' for ideas of how to prepare them. They are too astringent to eat raw. Sloe Gin is a classic. Sloe recipes

Thank you floral_uk, checking now the recipes.