The clip will feature in Taking On The Tabloids, a documentary aired tonight which follows actor Hugh Grant’s ‘Hacked Off’ campaign in the run up to the publication of Lord Leveson’s Report on his Inquiry.

Grant was given the never before seen footage and says: “The other day at breakfast just before the Tory conference, we were chatting to Charlotte Church and she suddenly remembered that she had interviewed Piers Morgan for a speech she was making and it was videoed and in it he talked about phone hacking. So she has lent us the DVD and this it.”

Morgan has always claimed he knew phone hacking existed and maintains he never knowingly used it.

The exchange between Morgan and Church is as follows:

Morgan: “There was a spate of stories that came out because of mobile phones. When they first came out mobile phones journalists found out that if the celebrity hadn’t changed their pin code, right…”

Church: “Yeah, you can access their voicemail.”

Morgan: “You can access, access their voicemail. Just by tapping in a number. Are you really telling me that journalists aren’t going to do that? If they know they can ring up Charlotte Church’s mobile phone, listen to all her messages…”

Church: “My God”.

Morgan: “Right, now all you have to do and I know it’s hard because celebrities don’t like doing anything for themselves is actually change your security number.”

Church: “Yeah, I’ve changed my security number”.

Morgan: “And now you don’t have to worry”.

Church: “Exactly”.

Taking on the tabloids airs tonight at 8pm on Channel 4