I have to say a quick thank you to Scott Allen, who wrote the excellent WP-SpamShield for WordPress. I had a problem in that people could not comment. He very quickly helped me identify the problem and get the comments working again (at least unless you are a spammer, in which case good luck!).
Basically the conflict seemed to be that I had the Social Plugin redrawing my Jetpack Comments that was throwing all sorts of problems with the Spamshield.
Scott quickly tracked the problem to Jetpack, but I was independently cycling active plugins on and off to identify the conflict the old fashioned way. I turned off Social and suddenly everything worked.
It turns out you don’t even need to deactivate Social but just the Comment redrawing that they do. So there you go. If you need a Spamfree WordPress run Spamshield, it will work with Jetpack, but not with Social Comments ticked. So untick that Social option and Robert is once again your father’s brother.
Right, now I can get back to my writing…