Can't add an ntlworld.com email to thunderbird

I had a couple of ntlworld.com email accounts in Outlook which worked well. Unfortunately Microsoft has just done an update and those accounts have disappeared. I tried to add them back and I found I couldn't. So I decided to add them to my Thunderbird instead. It couldn't auto set them after entering the email address and passwords so I tried to copy the settings from the email account that was working. Still it wouldn't set up the new accounts. Have virginmedia done something to stop me using other clients? If I log into virginmedia on their website I can see all the emails. What am I doing wrong?