It’s clear to me that by 1976, the series had exhausted its potential – and this immature and rather cheap wartime comedy sealed its fate. The suggestive character names seemed more appealing when read than when spoken aloud; for example, Kenneth Connor's main role as "Capt. S. Melly," along with his sergeant-major "Bloomer" (Windsor Davies), are preoccupied with preventing the men and women in their unit from engaging in any romantic escapades. Underwear is frequently being misplaced, flags become entangled, and there are even attempts to inject some life into the humor through tunnels, but they fall flat. The plot is overly familiar, and the earlier films’ gentle mischievousness has been supplanted by a rather vulgar level of bawdiness that feels rough around the edges. Joan Sims makes an effort to recapture some of the previous charm, but ultimately you understand how much more effectively James/Hawtrey/Williams and Hattie Jacques were at creating a humorous story with a touch of mischief. I’d recommend skipping this one, honestly.

Source on TMDB