Series 3

Mainwaring's lecture is a total mess due to gas masks. To obtain rationed petrol, Joe convinces Jones to volunteer his butcher's van as platoon car. Alas, after they worked for days to make it fit for the platoon, HQ has it converted to gas. Meanwhile, to Mainwaring's snobbish horror, vulgar grocer Hodges makes his haughty entry as ARP Chief Warden, and rival rooster in town and church hall.

It's Mainwaring's platoon's turn for a weekend of guerrilla warfare training at a rural facility. Thanks to train delay and the captain's disastrous sense of direction, they arrive late for dinner and sleep through breakfast. They do rather poorly at survival course, but Mainwaring's determined to redeem their honour by attempting a challenge nobody has ever pulled off: capturing the officer's HQ.

Mainwaring gives the platoon a lecture in communications but when a German plane crashes into the town's reservoir, it becomes obvious that many of the men have no idea how to use a telephone and, when Mainwaring gets through to the main exchange to notify the incident, the operator is no help.

Mainwaring is extremely annoyed that the platoon – sans Godfrey, who was too slow – have used up all their ammunition firing in vain at a low-flying German aeroplane. An inquiry is ordered – along with a new case of ammunition, which duly arrives. The captain in charge, taking place in the church hall in competition with choir practice, feels it a waste of time but talks the men through what happened.

An unannounced bank inspector from head office is far from impressed by Mainwaring's bumbling while handling some minor cash deposit and black market matters with Jones and Walker. He gets really angry about the way military HG considerations seem systematically to supersede bank interests. After an air raid alarm, an unexploded Nazi bomb is 'found' in the basement strong room and nearly made to explode by Mainwaring and Arthur. Bomb squad captain Rogers takes charge, but while he gets help, the men can't resist 'helping' themselves.

Wilson secretly enjoys passing on HQ Captain Bailey's finding that Mainwaring's captain's commission in the original local militia days is invalid, so he'll be reduced to lieutenant, as befits a platoon commander. When HQ concludes he's actually not even an NCO, he has to join the ranks under the Guard drill instructor he ordered himself. After the platoon's embarrassing failure at an exercise, everyone wants to have him reinstated, except Frazer, who smells opportunity.

A large field gun has been delivered for demonstration but none of the platoon know how it works. After a process of trial and error using models to represent the town, the time comes for the gun to be fired but the men get tangled up in the netting enclosing it.

After Mainwaring complains of sloppy slauting, a runaway barrage balloon appears with the Verger clinging onto it. He's rescued and various people, including Godfrey's sister Cissie, are asked to hang on until Mainwaring takes charge. Unfortunately, it takes off in the breeze with Mainwaring on the other end of its rope, dragging him through trees and a haystack until it stops on a railway bridge. The men are about to secure it but then an officer comes by and, in order to perfect the saluting so beloved of Mainwaring, they have to let go of the balloon.

Pike's work is suffering due to distraction from his girlfriend Violet, whom Mainwaring regards as common as her mother used to clean for him. Furthermore, at the upcoming platoon dance, Pike is going to announce his engagement to her, which alarms Wilson as Mavis would never let her baby go.

The platoon are on guard duty on a derelict pier, which they have reached by boat but, thanks to Pike's clumsiness, the boat has floated away, carrying their food. Hodges rows out in a children's boat to tell them to 'put that light out' and falls into the sea. Dispensary chocolate turns out to be a cardboard display but worse is to come when a floating mine appears.

Godfrey reveals that he was a Conscientious Objector during WWI, leading Mainwaring and some of the platoon to brand him as a coward. However, during an exercise in which Mainwaring collapses with smoke inhalation, it is Godfrey who, at risk to himself, rescues him.

Walker has found a discarded parachute which he cuts up to make ladies' knickers. This leads to an embarrassing examination of the ladies' pants to determine their colour as British parachutes are white and Germans are cream. Using a tracker dog, the platoon go into the woods where they trap a man with a foreign accent – but he is an Austrian birdwatcher hunting the rare golden oriole.

During weapons inspection, Mainwaring scolds Frazer for losing a single spring, rendering the Lewis gun useless, and HQ has no spare parts, so even a court-martial may follow. Frazer believes a coffin has been delivered to the funeral parlour, where the men discover it's at Mr Bluett's surviving brother's home. The hilarious treasure hunt continues even after the burial.

When a bank client's debt means his rowing boat must be auctioned, Mainwaring can't resist acquiring it for river patrols, however overstretched his men already are. Frazer supplements the nautical novice's Seascouts manual 'knowledge', and becomes the coxswain. But Mainwaring disregards all warnings, so they row through mist straight into sea. Hearing strange voices, they assume they are in Nazi-occupied France and hide, until they wake in a moving train.