Immigration a 'very real' concern for voters - Nick Ferrari
11 November 2011 Last updated at 11:32 GMT
Former defence secretary Michael Portillo said he was not as "excitable" as others over immigration numbers but broadcaster Nick Ferrari claimed it came in the top three of subjects for voters.
Alan Johnson explained the challenges of controlling borders, and security threats, while he was home secretary.
The panel was discussing Mr Ferrari's film on immigration.