Bah! My blog's been swamped with spam comments in Chinese (or possibly Japanese - please forgive my ignorance) characters. Apparently it's some kind of porn promo ...
It's happened before and I just deleted them but this time I was only able to delete a couple and got an error message re the others.
I followed the link to Blogger Discussion Groups and it seems this is quite a widespread problem (which hopefully they are dealing with).
So - don't follow the link in the comments - it only encourages these winkers (wink wink, nudge nudge).
And if you 're a techy and know how I can delete the comments, please share!