IT was the plan that would change the course of World War II and its success relied on one thing, the weather.
On Tuesday 6 June 1944, D-Day, 350,000 lives depended on the most important weather forecast of all time.
With conflicting reports, it fell to Dalkeith man Group Captain James Stagg to prove that his forecast was correct and then get the Allies to act on it.
His task, to persuade General Dwight D Eisenhower to change the date of the allied invasion of Europe from the fifth to the sixth of June.
At The King’s next week, David Haig’s play, Pressure, tells that very story. Based on the remarkable real-life tale of two warring meteorologists tasked with predicting the weather conditions for the D-Day offensive, the piece reveals the background to the forecast that shaped world history.
72 hours prior to the D-Day landings, meteorologist Stagg advised Eisenhower on the weather conditions likely to prevail when troops were to be sent across the Channel in Operation Overlord; he predicted severe storms.
However, Irving P Krick, the meteorological movie consultant relied on by Hollywood when planning film shoots, challenged that forecast with one of his own, he predicted beautiful weather.
With clashing opinions, the future of Britain, Europe and the United States rested on a single forecast that could not afford to be wrong.
Originally commissioned by the Royal Lyceum, Pressure, which also stars Haig, best remembered on TV as the hapless DI Derek Grim in the BBC police sitcom The Thin Blue Line, premiered at the Grindlay Street theatre as part of their 2014 season.
In the new touring production, he reprises his role as Stagg, and reflects it was his ongoing desire to take a “lateral look at history”, that inspired him to write the piece.
The 62-year-old explains, “I’m always searching for a lateral look at history; a story that is untold within the bigger story.
“Group Captain James Stagg is not the little man, exactly, but he’s a meteorological weather forecaster who has a huge impact on history.
“That little story with that microcosm within the macrocosm, as it were, is what fascinated me.”
He continues, “The play was a commission by the Royal Lyceum, who were looking for a lateral story about an unsung Scottish hero.
“John Dove, the director, rang me and asked me if I had ever heard of James Stagg, a dour but tenacious Scot, who virtually saved Europe after the invasion was postponed because of his weather forecast for D-Day.
“I didn’t know anything about him, he was just a name, and I didn’t know anything about the advances in weather forecasting at the time or indeed how archaic many of the techniques that the Americans brought over in 1944 were.”
It was Stagg’s understanding of how the jet stream and the power of the upper air currents affect the weather down below that made all the difference, reveals Haig.
Depicted as tenacious, a bit rude but with huge integrity, it was ultimately Stagg’s blunt honesty that won Eisenhower’s confidence, despite his brusque manner and occasional unpleasantness.
Consequently, Haig admits he was initially reluctant to take on the role, although there was another reason.
“The first thing that happened is that we failed to get the incredibly famous Scot we were after for the role and once we hadn’t achieved that casting, it became more logical for me to do it.
“But I didn’t think of myself as natural casting when I first wrote it.
“I had no intention of playing the part and it was only when other people persuaded me I’d written a part that suited me I began to realise perhaps he did suit me after all.”
Laughing, he adds that he’s looking forward to returning to the role because he “already know the lines.”
On a more serious note the actor concedes that, “There’s an inner tension that Stagg is seeking to control that’s always interesting to portray.”
A play about “heroism in integrity”, “heroism in honesty despite all the influences around you” and the “heroism in ordinariness”, bringing Stagg to life on stage provided Haig with more than a few challenges, not least because, although the play may be about the forgotten hero who ‘won the war’ for the Allies, the star is the story itself.
“Every role has challenges. Often a character can almost define a play but with this one the story is the greatest character.
“The lead part is the weather and the characters serve it. That’s fascinating in itself, but this guy, through his perseverance and tenacity, is someone we have a huge amount to be thankful for because if the invasion had gone ahead on the original day, 5 June, probably around 80,000 people would have died in the gale force winds.
“All the landing craft were flat-bottomed and they simply wouldn’t have got across the Channel.”
Bringing the play back to the Capital, where it all started, gives the current production a particular significance adds Haig.
“Edinburgh is somewhere I’ve performed many times before and somewhere I’m really looking forward to going back to because James Stagg was from Edinburgh, or rather he was from Dalkeith, just outside Edinburgh.
“We had sell-out houses last time we did the show there and the King’s Theatre was very keen for us to come back with this Edinburgh story, so there’s a built-in excitement.”
Pressure, King’s Theatre, Leven Street, next Tuesday-Saturday, 7.30pm (matinees 2.30pm), £18-£31.50, 0131-529 6000