It gets worse
Checkout http:/nhsblogdoc.blogspot.com and the articles "MTAS site closed for "essential maintenance"" and "MTAS - would someone tell me this is not true" from today.
Apparently any applicant could see email to other correspondents by changing the number at the end of the redirect url to the MTAS site. Also anyone could sign up for the MTAS site without proof of who they were, so this information could be seen by anyone.