Musical walk into the past

The Pilgrim's Progress - Composed by Ralph Vaughan Williams and performed by The Royal Opera. Barbican Hall, Tonight

It is telling that this production was commissioned for the 1951 Festival of Britain at a time of great transition - strong moral allegory can work wonders during an era of change, and the festival turned eyes from the horrors of the Second World War towards the regenerative effects of the consumer boom.

Ralph Vaughan Williams's composition and John Bunyan's allegorical story walk together in reliance on tradition and an appeal to the idealised past - but this will not be the only assurance of seamless translation of text to music, as Bunyan's allegory relies upon the premise of simplicity and universality.

The narrator embarks on a pilgrimage through the seven deadly sins, allegorised as places like the Slough of Despond, The Interpreter's house and the Valley of Humiliation, meeting people characterised as Mr Worldly Wiseman and Faithful along the way.

The history of John Bunyan's allegorical story, is a confusing blend of traditional morality and burgeoning liberty. This strong Christian allegory was written in the 17th century when Bunyan was in jail for preaching without a licence. Certainly he speaks with an authority that can make you wonder whether he should have a licence from God.

Ralph Vaughan Williams is also a paradox as an agnostic who composed Christian music. Williams was proclaimed as the quintessential English voice, which in a 20th-century composer open to European influence, was quite rare.

Looking backwards to traditional folk music, Williams once said he was "like a physical researcher who has actually seen a ghost".

It's enduring success as a universal allegory is testified by it's original circulation among the uneducated and that it has since been translated into well over 100 languages.

Barbican Hall, Silk Street, EC1 at 7pm. Tickets pounds 11-pounds 32 (0171-638 8891).