I've just come back home to find my skype account has been deleted/removed. Apparently an old email I closed down, despite no longer being linked to the skype account, was still linked and has scrubbed the lot. I'm currently trying to get the account back so in the meantime if you need me, fire me a forum PM.
Update - Microsoft are utter idiots so my previous account has been completely deleted so if folks could re add me, my new account is dgc-Croft@outlook.com (yes, skype no longer allows you to chose nicknames) it would be much appreciated.
It's more the account management system than skype itself that caused this mess, though you can prevent ads on skype by blocking an IP in your internet options.
At least its one way of purging old contacts, if not a tad excessive.