Lysimachia

A bit of a lazy blip for a lazy day (making up for yesterday's busy day and better-than-average-by-my-standards blip). Spotted this growing in the garden but I don't have a clue what it is. Any suggestions?

Edit: the prize goes to guiri - it's a Lysimachia. The next question is - where did it come from? We've never had one in the garden before!

Another busy week beckons, starting with a trip to Taunton tomorrow, so I might not be commenting much in the next few days ...