Famous as a radio presenter, comedian and novelist, Sandi Toksvig possesses yet another side to her exuberant talents, as a writer for the stage. After supplying the book for the musical Big Night Out and co-authoring the comedy Pocket Dreams, she next turned her attention to serious drama. Bully Boy, which studies the effect of wars on those we send to fight them, opened to critical acclaim in Southampton last year. With the same two-strong cast — the hugely respected Anthony Andrews and charismatic newcomer Joshua Miles — it is at Northampton’s Royal&Derngate before moving to London where it will open the new St James Theatre, Victoria, on September 18.

Running for one hour 40 minutes without interval, this taut and gripping drama explores in vivid detail the unusual across-the-classes friendship that springs up between a 20-year-old squaddie accused with colleagues of a war crime in Afghanistan and a major sent to investigate the offence.

An eight-year-old Afghan lad has been dropped to his death down a well. It appears to be the work of the Bully Boys, among them Burnley-born Eddie (Miles).

Their name, he tells investigator Oscar (Andrews), is not a reflection of their conduct to the locals but because one of their number is in the habit of crying “Bully for you!” at moments of celebration.

Oscar, we sense, might not believe this, after hearing the youngster’s many references to ‘camel jockeys’, ‘towel heads’ and the like.

Confined to a wheelchair through injuries received during the Falklands conflict, Oscar is revealed to have his own issues to contend with, including the fact that he is a closeted gay with an obvious interest in Eddie.

Toksvig indicates his homosexuality in a manner to which some might object, by showing he conforms to the stereotype in being good to his mum and especially fond of ballroom dancing and cheesy 1980s pop.

After that, though, there is nothing in the least predictable in watching how their relationship — no, let’s more fairly say association — proceeds.

Their interaction is shown in a series of meetings, some of them friendly and some not, spread over months at home and abroad. They span a calamitous event affecting both their lives.

These are simply staged by directors David Gilmore and Patrick Sandford with minimal props — a table, various metal chairs — arranged before an angled, slatted backdrop on which are projected images to suggest location. This technique focuses attention firmly on the actors whose utterances tell us so much about what is inflicted on soldiers by those who send them into battle.

Toksvig’s anger, with Thatcher, Blair and their ilk, emerges clearly from these exchanges. So, too, does her pity and compassion for the suffering men.

Royal&Derngate till September 15. 01604 624811 (www.royalandderngate.co.uk). St James Theatre from Sep 18. 0844 264 2140 (www.stjamestheatre.co.uk). Sandi Toksvig is at Oxford’s New Theatre on Sunday, September 23, with a night of stand-up. 0844 871 3020 (www.atgtickets.com/oxford).