If your concern is to keep the accounts, but not on Thunderbird, just highlight the accounts, rightclick and select 'settings', then scroll down to 'account actions' and click delete.

Hi David, & thanks for your quick follow up. Following Virgin's re-instatement of the email service, I have now two email accounts for "john.marris1@ntlworld.com" on Thunderbird. When I right click on the address that is surplus & follow your instructions, after pressing delete I receive the following "An account with this name already exists. Please enter a different account name." I have another address - "mazawatea@ntlworld.com" with two entries on Thunderbird! This all occured as I installed a new computer!

My suggestion would be to edit one of them to be 'different', such that TB doesn't think it is the same. I think that should 'trick' TB into allowing the delete.

Thanks Dave, problem solved!

You're welcome.