Comments temporarily restricted to newer articles

For some weeks, this blog has been targeted increasingly by one specific source of comment spam. I am afraid that I have therefore blocked all further comments on articles which are older than forty days, as a temporary measure.

I will remove this block in twenty-four hours, and see whether this shuts those offenders down.

I greatly value your comments, and would never wish to limit them unnecessarily. Please forgive this temporary measure to address this problem.