After a very foggy morning it has poured heavily since noon and seems likely to continue until Friday.  Fortunately I had a walk before the rain and spotted this fairy foxglove (Erinus alpinus)  growing in profusion on an old wall.  It is no relation to the common foxglove. The tiny pink plant is about 6 inches tall and likes to grow on old walls such as castles where it can root in the lime-rich mortar. There are several places where it can be seen including the Nun’s Bridge in Haddington and a wall in Musselburgh.  It is fairly common in southern Europe, around the Mediterranean and some parts of the Alps and is becoming established in parts of Britain, probably having naturalised after originally a garden escape.
This  is an interesting article about fairy foxgloves