Two wrongs, the proverb tells us, do not make a right. Ronald Harwood's new play {An English Tragedy: L1823395882}, receiving its world premiere at Watford, uses the story of John Amery to make this point.

Amery had a privileged upbringing. He was the son of a Cabinet minister, educated at Harrow and Oxford with all the prospect of the successful career his father's contacts, including Winston Churchill, might facilitate. Yet he frittered away his chances and his father's money, lived and drove in the fast lane and ended up as a propagandist for the Nazi regime in Occupied Europe. Then came 1945 with its total Allied victory over Germany; the outcome was inevitable. He was 33 years old.

As with so many Hitler supporters, the mainsprings of Amery's political philosophy were negatives - anti-semitism and anti-communism. His was a world of black, white and red with no half-tones. These by themselves do not necessarily make gripping drama, but Harwood has been far more subtle than that. He shows us the half-tones, and then dissects them. The play is beautifully written to balance its elements of frenetic comedy and fog-wraiths of pain and horror.

And it’s given the production and performances which it deserves. Richard Goulding is incandescent as John Amery, switching seamlessly from the dangerous nonsense of a Bright Young Thing well past its sell-by date to brittle courage and outright fury. The agony of Leo Amery, the father with secrets whose breakdown is painful to watch, is equally palpable in Jeremy Child's characterisation. This is a man with whom you may not agree but can understand and suffer with.

Similarly, Lucinda Millward's Dr Pimlott. But not so with Leo’s wife (Diana Hardcastle), whose nickname Bryddie hints at her own fragile mental equilibrium shattered in her last meeting with her wayward son. This is yet another heart-rending performance in Di Trevis' fine production.

Ralph Koltai's set - a red and black swastika which shatters into raked acting areas - throws the action into proper relief and continually reminds us of the shadows into which the Second World War plunged all of Europe. This is a dark world in which dark things happened. But the people that Harwood presents to us are not shadows. They are real. They suffer. We understand.

- Anne Morley-Priestman