It seems blogger have broken something - no matter ho much I clear cookies and so on, I am not able to comment on my own blog!
It used to be that it understood it was me, allowed me to edit posts directly from my blog, and comment, and reply to comments as me.
Sadly, it is not doing that - I have to go in to blogger and from there I can make new posts and edit posts, but even then I am unable to actually comment or reply.
So if you are wondering why I have not replied lately, blame blogger.
P.S. Apparently it is not just me! Thanks for confirming, Neil.
P.P.S. looks like using incognito actually asks me for my login, and then oddly the main browser window knows who I am, WTF? So, err, fixed now.
P.P.P.S. and magically, a little later, it forgets who I am again and won't ask me for a login. Grrr