I first saw this in the wild in the south of France about 30 years ago or more whilst I was out there replanting a garden for a client. I was fascinated by it as it looks like a thyme but is a relative of the primrose, a favourite family of mine which also used to include Cyclamen. I brought a few seeds home with the intention of growing it in a pot in the greenhouse. I couldn't get it to germinate just sat in the greenhouse and was about to give up and decided to pop it into the airing cupboard. Within days all of the seed germinated! It grew well for a few years before I lost it.
This May whilst visiting Brian Constable in Catalonia I saw lots of it mostly in full flower and in varying shades of magenta pink. Here's a picture from that visit.
I have placed it here because although it has a woody base it is more of a sub-shrub which many people would include in herbaceous. E.g. Bergenia, Primula auricula, Dianthus etc.