"Room at the Bottom" is the sixth episode of the third series of the British comedy series Dad's Army that was originally transmitted on Thursday 16 October 1969.
Plot
Wilson is sitting at Mainwaring's desk, when Captain Bailey from GHQ arrives. He asks Wilson about how long Mainwaring has been in charge. Wilson says it was ever since they were Local Defence Volunteers. Bailey is surprised because there were no commissions in the LDV, and Wilson admits that Mainwaring made himself a captain. Bailey tells him that it is more ordinary to have a lieutenant in charge of a platoon, so Mainwaring must remove one of his pips. Wilson is delighted and is even more delighted when Walker brings him his new hat: a beret.
Wilson, with some glee, practises what he is going to say to Mainwaring, who then arrives, announcing that he has recruited a Drill Sergeant for drill practice. Wilson tells him about Bailey's visit, but Mainwaring laughs it off. He rings GHQ and speaks to a sergeant, who knows nothing about it. He waits for Wilson's explanation, and concludes that Wilson is jealous of him, and that is the reason why he bought a beret. GHQ rings; Mainwaring answers and is horrified to learn that Wilson was telling the truth. Wilson insists that he is sorry for Mainwaring, even though he is laughing in his face.
Godfrey sees Mainwaring removing his pips, offering to assist based on his former experience in tailoring, but is quickly dismissed by Mainwaring, who is determined to make sure nobody finds out, but Godfrey blabs to the rest of the platoon. Frazer, Jones and Walker wonder whether he has been promoted to major, though Walker hopes not, believing that Mainwaring is pompous enough already. When the parade is about to be dismissed, Mainwaring emerges from the office with a rubber tyre on his shoulders, covering up his badge of rank. Walker and Frazer point out that they cannot salute Mainwaring unless they can see his rank. A reluctant Mainwaring is about to reveal the truth, when the Verger comes rushing in, announcing that the Bismarck has been sunk. The platoon cheer and Mainwaring quickly dismisses them, the Navy having "saved his bacon".
The next day, Captain Bailey returns and tells Wilson that Mainwaring has not even been commissioned as a lieutenant, and he must join the ranks. He adds that Wilson will be in charge for the time being. Bailey gives Wilson the news in an envelope and leaves via the main hall so as not to disturb the platoon's drilling. Mainwaring then arrives and opens the letter as Wilson quickly leaves the office. He hears a shot and thinks Mainwaring has committed suicide. He rushes in and is joined by Jones, who explains that it was Godfrey's rifle that fired, and the two of them help a speechless Mainwaring into his chair.
Wilson commands the next parade and admits he will be leading them on the divisional scheme on Sunday. Mainwaring enters, wearing a private's uniform, nobly declaring that the protection of the town must come before pride. The platoon, particularly Jones and Godfrey, are saddened as he joins the ranks. Wilson calls the platoon to attention, but Mainwaring mistimes his drill, while Jones has improved. However, the roles are soon reversed.
Suddenly the pre-arranged Drill Sergeant Gregory turns up and immediately starts barking orders, insulting many members of the platoon. Mainwaring speaks up in their defence but, now as a private, is picked on for speaking out of turn. However, Gregory is soon given a taste of his own medicine when they practise sloping arms; Jones mucks it up, accidentally throwing his rifle on the Drill Sergeant's foot.
At the exercise Wilson does not make a good job of leadership. Jones volunteers to be the scout, but ants climb up his trousers and he has to take them off to get rid of them. Believing this is the signal to advance, the platoon moves forward but soon find themselves in an ambush. It is a disheartened platoon that heads back to Walmington. Sponge remarks there will be no platoon left for the new officer to take charge of. Therefore, the platoon decides to write to GHQ, asking for Mainwaring to be commissioned. In his letter, Walker offers a couple of bottles of scotch "if it will tip the balance". Frazer declines to write with his colleagues, instead writing at home and asking for promotion himself.