I am afraid that this blog has once again been under a spam attack all day, in which spammers are trying to post spurious comments at a rate of about one every minute.

I have therefore had to limit comments to those who are already recognised by the blog, or who log in to make their comment. I am very sorry that this will make it more difficult to add a comment for some. Once the attack has gone away, I hope to be able to ease that restriction again.

Please don’t let it inhibit your use of the blog, or making comments.

Update:

The avalanche of spam comments appears to have stopped at last, and these restrictions have now been removed. Please comment freely!