Set in Philadelphia in July 1960, at one of the national political conventions, this is a play about power, corruption and morality. It’s a race between two men who seek their party’s nomination for the American presidency. Both men are flawed; William Russell is promiscuous and his marriage is in trouble, while Jo Cantwell is ruthlessly pragmatic, believing his ends justify the dirtiest of means. Human nature is such that no one is beyond reproach, but as presidential candidates, their private lives become public property – and the outgoing President needs to decide who to support.

Gore Vidal was a novelist and letter-writer as well as a playwright, but this script was inspired by his own bid for power in 1960, when he stood unsuccessfully as a Democrat in a pro-Republican district of New York. Mr Vidal said the character of Jo Cantwell is loosely inspired by Richard Nixon, but there are surely traces of the Kennedys there too. Secretary William Russell is based on Adlai Stevenson, an intellectual with a conscience and a commitment to peace.

William Russell is played skilfully by Martin Shaw, an accomplished theatre, film and TV actor. As the race becomes bloody, you watch this man search for a moral way to defeat his opponent. Russell dislikes the compromises of politics, but as outgoing President Hockstader says sadly: “To want power is corruption already… it ends in the grave, where it goes to dust.” As Hockstader, Jack Shepherd provides a shrewd commentary about political life, its trials and tribulations; he says strength and decisiveness is everything in a President, but is he right?

Glynis Barber is also strong as Mr Russell’s wife, Alice, offering discreet support her husband may not always deserve. However, Honeysuckle Weeks gets the most laughs as Mabel Cantwell, wife and “mama bear” to Senator Jo Cantwell, particularly when the three women meet. Her husband, played by Jeff Fahey, is also compelling and credible in his ruthless pursuit of power; the contrast between domestic respectability and dirty political games works well, and we discover Mr Cantwell has a dark secret.

Anthony Howell plays a special advisor with alacrity, although his role provides fewer surprises and potentially less scope. Gemma Jones offers some good humoured, feminist satire as Mrs Gamadge. Characterisation is good throughout, and the script is clearly well-researched, with unpredictable twists in the plot to keep the audience engaged and personal battles that the characters cannot always win. Densely packed with dialogue, this political thriller is written by an insider with imagination. It's gem for those interested in politics, but I think it’s also a play about corruption of the human spirit – which is a universal theme, accessible and relevant to everyone.