“I sashayed over to the gramophone.” With that one line, you’ve got the measure of Pamela More – society darling, Times columnist, and thoroughly independent woman. More’s a fictional character, but the world she inhabits seems sparklingly real: she lives in a 1930’s playground, surrounded by high society and haute couture. But of course, we all know what happens next… and sure enough, the storm clouds gathering across the sea in Germany soon begin to cast a shadow over More’s privileged life.

Most of the story’s set around the Abdication Crisis of 1936; a time when war seemed possible but not inevitable, and the horrors already committed in the name of Nazism were all too easy to ignore. At first, More sees the situation entirely through the lens of fashion – Hitler’s uniform is rather over-the-top, she feels – but as time goes on, she begins to understand that the world beyond her round of society parties has become a disturbing one. An interview with Wallis Simpson, fashion icon and lover of King Edward VIII, sets More up for a new life of intrigue. At first she just eavesdrops at parties – but before the play is done, we see her jumping from an aeroplane into wartime France.

Rebecca Dunn delivers an accomplished performance as More, commanding the stage and leading the audience effortlessly through a relatively complex monologue. Her polite but haughty manner – behind that posh accent, there’s a big dose of snobbery – segues into naïve anguish at the evil taking hold in Europe, and she’s surprisingly convincing as an action woman, too. The other characters could perhaps be more clearly evoked; it’s More’s story and it’s told very much in More’s voice, but on the whole the performance drew me successfully into the tale.

So this is a nice period piece, and playwright Sarah Sigal effectively carries us back to the potent age of the 1930’s. But it needs an extra something to take it to the next level. Although the whole story is told in flashback, it’s very straightforwardly done; I’d have liked a bit of portent or regret, the sense that More is speaking now with the benefit of hard-won hindsight. The beautifully evocative set, capturing the essence of Blitz-torn London, sets the scene perfectly – but we really learn nothing of how this paragon of refinement is coping with the privations of war.

I also feel the potential of wartime Lisbon is somewhat under-used. Portugal was a neutral country, and there’s some excellent scene-setting, describing Allied and Axis planes standing beside each other on the airfield and the poignant way that exiles wait for loved ones left behind. But our own stay there is all too brief. Overall, I was left with a sense of a play that takes a long time to get going, and then – just when things grow properly interesting – draws quickly to an end.

When all’s said and done though, this play’s about Wallis Simpson as much as it’s about Pamela More, and the theory it advances (though far from proven) is a credible and interesting one. So Agent Of Influence is an enjoyable play, successfully spanning the transition from decadence to war. The concept’s sound and the details are good; the structure just needs a little bit of tweaking.