The photos that appeared on social media of former energy secretary Chris Huhne eating breakfast with artist Grayson Perry in a motorway café less than an hour after his release from prison were baffling to many. But now the reason behind the encounter has been revealed – it was the basis for a new artwork.

Perry's portrait of the disgraced former politician will go on display as part of a new exhibition at the National Portrait Gallery, it has been announced today.

The portrait, which won't be revealed until 25 October, is one of 14 produced by the transvestite artist for a Channel 4 series entitled Who Are You? in which Perry examines how portraiture is linked to British identity.

Perry interviewed Huhne for the show within one hour of his release from jail where he had served 62 days of an eight month sentence. Huhne was convicted of perverting the course of justice in 2013 over news that his wife accepted speeding penalty points on his behalf. Huhne's ex-wife Vicky Pryce was sentenced for the same offence and was released on the same day.

Perry's series will be broadcast as three one-hour films in October. In each he spends time with people who are at a definitive point in their lives and then uses those impressions to create their portrait. Other portraits in the collection include Northern Ireland Loyalist marchers, a transsexual, deaf parents, a Muslim convert and X Factor contestant Rylan Clark.

"I have always been interested in the things we tend not to think about or take for granted, like our sense of aesthetic taste," Perry said. "In this show I investigate our slippery sense of who we feel we are.

"Identity seems to be something that is only an issue when it is threatened or problematic in some way."