As far as I know, so called ornamental blackcurrants still produce edible fruits - the 'ornamental' refers to certain varieties which have more attractive leaves (variegated or colourful). Blackcurrant is Ribes nigra; you may be thinking of Ribes sanguinam, the ornamental flowering currant, which is not grown for its fruits, but for its flowers.

Pretty sure you can eat them anyway, they won't be poisonous. try one and see if its sweet.

They are similar to cherry, some cherry trees are grown more for their flowers not for their fruit as it's usually bitter, small, or not nice to eat. As others have said, they are still edible but might not taste nice. You could always add lots of sugar and make a cordial, or mix them with sweeter fruits, etc.

Thanks all!
I have tried the fruit, it was quite bland but not disgusting!
It tasted a little like edible blackcurrant but I am not sure if it's just because it smelled so strong. I reckon with enough of them there would be a blackcurrant flavour.

Thanks again for your help :)