Back in the undergrowth

I've spent a lot of the last few days giving my website the (overdue) spring-clean it deserves - almost done, but it does mean that I've not ventured far from the desk. These little purple flowers are everywhere in the garden (does this make them weeds?), but I'm not sure what they are.

We thought they were Vinca - but they don't seem to match the images in the gardening books or websites. Will need to refer to a higher authority.

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