There are countless stories of heroes signing up to do their bit during the first World War. This one concerns the football club Leyton Orient, then known as Clapton Orient. They were the first football club to sign up en masse for the war effort; 41 members of the squad and backroom staff all left their lives at home to volunteer on the frontline.

The play kicks off with a pretty jovial look at 1910s England; two boys instantly become best friends just because one of them has a football. Michael Head brings humour to scenes where chunky 'Jumbo' beats the entire team back from a training run after hopping on a bus. But don't be fooled, this is a play of two halves. Act two is a full-on war drama: fans sign up to follow their heroes, brothers die in arms, friends make the ultimate sacrifice. The football boots are well and truly swapped for combat ones.

Generally, the show is paced well, but certain calls by director Tilly Vosburgh put the brakes on. The abrupt halt as two wives sing their heroes off to war is bizarre, and interludes with newspaper boys shouting "Extra! Extra!" attempt to move the story on smoothly, but are simply irritating and gratuitous.

The set by Suzie Ingils is simple - one wall plastered with 'Your Country Needs YOU' posters and six wooden boxes - which leaves the players to do the talking on the pitch. There are some great performances; Charlie Clements (EastEnders) plays a fierce but proper team captain-turned-commander, Peter Hannah is moving as Geordie McFadden who relocates to London with his wife to play for "The O's". Nick Hancock (They Think It's All Over) is disappointing as the club manager whose only motivation is to shout "come on lads, we've got [insert team name] on Saturday!". His scenes which should show the compassion he has for the players and their wives are marred by a wooden performance.

As the final whistle goes, at two hours 20 minutes, it feels as if we are deep into added time. It's as if Head tries to tell a story for each and every player, and wrote three or four possible endings but can't decide on which is best, so shoves them all in at the end.

But none of this mattered to the Orient fans and Chelsea Pensioners sat in front of me on press night, who wrapped their arms around each other and wiped away tears as the curtain came down on this stirring but flawed play.

The Greater Game runs at Southwark Playhouse until 15 October.