Melissa Blease reviews Pressure, starring Olivier Award-winning actor and writer David Haig, on at Theatre Royal Bath until Saturday 17 March

Michael Fish, Carol Kirkwood, John Kettley; Ian McCaskill, Fred Talbot… and James Stagg. If we’re playing ‘spot the odd one out’, it’s likely that many of us would go for James Stagg – the other five have all been (or still are, in the case of Carol) legendary national TV weather forecasters. So what’s this Stagg fellow doing in the line-up?

Ah, gotcha. Group Captain James Martin Stagg (CB, OBE and FRSE) was the British Royal Air Force meteorologist who in 1944 persuaded General Dwight D Eisenhower to change the date of D-Day – the Allied invasion of Hitler’s ‘Fortress Europe’ – from 5 June to 6 June 1944. The rest, as they say, is history.

Pressure, a new play written by and starring, in the lead role of Stagg, multi-award-winning actor and writer David Haig, is set in the Portsmouth HQ of the Allied Expeditionary Force, with the action unfolding over the 72 hours leading up to the Normandy landings, codenamed Operation Overlord.

Haig is subtly captivating as Stagg, the dour, pensive Scotsman whose predictions for weather are as guarded as his personality. He insists, based as much on his intuition as on the weather maps and reports, that the invasion must be delayed because of impending storms in the English Channel. Stagg clashes with Krick, a polished performance by Philip Cairns as the brash, data-focused go-getter who, in 1938, established the first private weather business in the US, set up largely to advise America’s burgeoning movie industry (Krick famously forecast the weather for the shooting of the burning of Atlanta scene in Gone with the Wind). Krick insists that high pressure over the Channel will guarantee fine weather on 5 June, allowing the invasion to proceed as planned.

Ultimately, it is up to Eisenhower – brilliantly captured in his charismatic, authoritative but contemplative essence by Malcolm Sinclair – to decide which of his two highly-regarded advisors are correct in their predictions. With the lives of 350,000 Allied soldiers, sailors and airmen resting on Eisenhower’s decision, the pressure – in all senses of the word – is on.

Weaving in, out and around all three men, Lieutenant Kay Summersby, chauffeur and personal secretary to Eisenhower, brings prudence, rationale and much-needed tenderness to the increasingly stressful situation. In a perfectly-paced performance by Laura Rogers, Summersby is the anchor that keeps the three men grounded while the storms of war – quite literally – rage around them. In one particularly moving scene, she supports Stagg as he learns that his wife, who had a difficult labour with their first child, is about to give birth to their second child without him by her side. In another memorable moment, she must deal with her own disappointment as it becomes clear that Eisenhower does not, after all, intend for their apparently intimate relationship, hinted at here, to continue after the war (historians are divided over whether or not the two conducted an affair).

Throughout the drama, debates rage, tensions rise, weather charts are updated, and characters and personalities clash. On a breezy level, the ebb and flow of the relentless anxiety is a metaphor for the unpredictable, swiftly-changing British weather patterns that Krick finds so difficult to understand, but of which Stagg has an instinctive understanding.

But ultimately, the story behind Pressure is as real and tangible as pressure ever gets, touching on the potentially momentous consequences of both personal and professional decisions, the burden of power, the philosophy of war… and offering us a unique opportunity to witness history in the making which puts our the British preoccupation with the weather firmly into perspective.

Main image: Laura Rogers as Kay Summersby and David Haig as Group Captain Stagg in Pressure