Geranium, mabye Rozanne, Orion or Johnson Blue. If it gets out of control, you can cut it by half and it will grow and rebloom.

geranium

what one might call .. the perennial geranium.. as compared to the big showy Gs usually grown as annuals.. or half hardy pot plants.. depending on zone ...

ken

Thank you everyone for all your help. I can now sort out how to prune it. Take care - Rockpiler

It doesn't need any pruning since it is not a shrub or tree. As unbiddenn mentioned it can be cut to the ground and will regrow. At the end of the summer it will all die back to the ground and can be tidied up either in autumn or early spring. It will reappear next year.