It grows as reasonably hardy herbaceous perennial in Hertfordshire, UK, but would no doubt persist above ground in a more gentile climate. Grows to about 2ft, stems square. Leaves are a pale green, fairly smooth, not sticky. I haven't seen it in any of the usual references - Yeo, Clebtsch, Salvia Guy or Robin's site - makes me wonder if it really is a Salvia. When it flowers this year I really must take a closer look at the flower detail to get some botanical clues!
It certainly looks like S.lavanduloides. But what time of the year was your photo taken? I used to grow this, and I am in Surrey, UK, but never had it in flower until October. The cacaliaefolia underneath it looks healthy!
Thanks Cait & Robin. I must admit that lavanduloides was the closest match that I could find but somehow felt it didn't fully tie in. The pics were taken 4/9/06 and 1/11/06. I've added a further pic to this post taken 22/8/06. Robin, if you'd like a cutting of my plant, I've sent you an e-mail and we can link up from there. Jim