Thanks for this.
With a bit of trial and error I found out that the BT Virus Protect Firewall was the culprit. I turned it off and got normal full email access. I reported it to BT tech support and after letting them have screen access they agreed and will refer it up their management chain.So no result and poor customer service in my view.
I will delete it(it is a McAfee variant) and put Zone Alarm free on as security.