Judi Dench and Steve Coogan make an unexpectedly terrific double act in this touching, funny and thoroughly captivating film based on a true story.

Dench is typically brilliant as elderly, working-class Irishwoman Philomena, who’s desperate to trace the son she was forced to give up for adoption in the 1950s, and Coogan delivers an assured performance as cynical, Oxford-educated, ex-BBC journalist Martin Sixsmith.

Approached by Philomena’s daughter (Anna Maxwell Martin) in 2003, Sixsmith is smarting from being sacked as a spin-doctor to Tony Blair and is initially reluctant to help Philomena, but he eventually agrees to investigate her story, hoping to turn it into a lucrative human-interest tale.

The naive Philomena and jaded Sixsmith duly hit the road, going first to Ireland and then America in their quest to discover the truth.

It is an exquisitely funny journey, which only makes the story they uncover that much more heart-wrenching, and the whole movie is put together with great skill by director Stephen Frears, working from a Bafta-winning script by Coogan and Jeff Pope.