There are now a million undocumented - or ‘illegal’ - immigrants in Britain, many of them settled here with families. When Boris Johnson edited The Spectator, he argued that an amnesty should be offered to those who have been here for a long time. He retained the policy as London Mayor. Is it now time for him to implement it? Would such an amnesty be a bold expression of liberal conservatism - or a dangerous weakening of Britain’s borders and security?

Join editor Fraser Nelson and Kate Andrews, The Spectator's economic correspondent, who both argue for amnesty. David Goodhart, head of immigration at Policy Exchange and Alp Mehmet, chairman of Migration Watch UK will argue against. The debate will be chaired by Katy Balls.

Doors open: 18:30

Event starts: 19:00

Event finishes: 20:15