Many of us have been searching for this for a long time. An enterprising chap called Rob MacGregor has found a copy of the part of the South Bank Show where Melvyn Bragg interviews Paddy for 15 entertaining minutes. It has been uploaded to You Tube. As we know these things can be swiftly removed due to copyright issues so if you wish to view Paddy in one of his best interviews I would advise taking time to view quickly.
Here is the direct link to You Tube.
As an alternative you might try to download the video. There are a number of programs available if you search on Google.