I would suggest an Arabis, possibly blepharophylla (just because I was looking at this in the garden a few minutes ago!)?

Beat me to it!

Can only be by seconds then, Owdboggy!

So who is the fastest gardener in the country? lol. Thank you both. It is a smashing little plant and I found a very similar photo of it on this website once you had given me the ID. http://www.seasonfl.com/front/php/product.php?product_no=3367&main_cate_no=1&display_group=3
It has a lovely scent. I got it in an outlet in South Yorkshire when I was buying other plants.