Another Lost Label

I can't remember the name of this small rhododendron. I know it belongs to the lapponica group, and it is called blue something, or something blue. 

Googling hasn't come up with a convincing answer, though it tells me that they are sub-alpine and sub-arctic, which would explain why it grows happily here. 

One of those no-further-than-the-garden days, in fact mostly indoors, where normality has almost been restored.