Dick (John Moulder Brown) has gotten into trouble today after breaking a window at school accidentally, and the headmaster has ordered him to go to his office the next day. But his troubles are not over, because once he gets home he realises he's forgotten to bring his homework with him and has to return to the school in the hope that it's still open. Meanwhile, rag and bone man Paddy (Sydney Bromley) has been told by his boss Skinner (Derren Nesbitt) not to take his horse to collect a batch of junk from the school, and to take the lorry instead - his path will cross with Dick's.
Operation Third Form was a production of the Children's Film Foundation, which by that time was well into its second decade of providing distraction for the nation's kids on a Saturday matinee, although they were by no means universally loved, because there was grumbling among some of those subjected to them at the weekend while their parents went shopping that they would much rather be watching the kind of film the grown-ups got to see. Challenging the C.F.F. was not, and this example is almost the typical effort from them with its youngsters foiling the criminals plot, though there were moves here towards modernity.
After all, the kind of thing its audience was watching on TV was The Avengers and The Man from U.N.C.L.E. where spies were holding court with all the technology they could muster at their disposal, so instead of Napoleon Solo opening Channel D we had our plucky gang making best use of the capital's telephone boxes (oddly, the thought of walkie talkies never crossed their minds, or more likely was beyond their means). Why were the kids deploying one another with such military precision, even to the extent of having an operations room? It was all the fault of Skinner, a cliché C.F.F. villain if ever there was one.
Basically the sixties version of a spiv, he manages to get hold of the school's bell, donated to the place from his ship by a bluff Admiral (William Sherwood); how he does this is quite complicated, but basically when Dick is in the school after hours fetching his homework Paddy is there too and thinks he's a burglar, then a ghost (?!) and rushes off, accidentally catching the bell on the back of the lorry and driving away with it. Dick is witnessed fleeing the scene by the caretaker and is blamed for what the head thinks is a theft - which it is once Skiinner sees what he has at the junkyard, hiding it under the floorboards of his office though not before the intrepid Dick has caught sight of it.
Naturally no adults will believe his story, but his fellow schoolboys will and so does his little sister (Roberta Tovey, shortly after playing Doctor Who's granddaughter in the movies), so a plan of action is drawn up. Seems Skinner not only wants to sell the bell, but steal the Admiral's priceless painting too, therefore tailing the miscreant's every move is the order of the day, a job made a lot easier by the fact that he doesn't have a car and walks everywhere when he's not taking the bus. Nesbitt by this time was carving a niche as sharp-dressed dodgy geezers and was well cast here, just the sort of character kids would want to see get their comeuppance, but don't go expecting any nailbiting tension, or even excitement on the level of your average, contemporary TV adventure show, as usual with such affairs it was quaint, and ended up with not one but two adults falling in the water. For Moulder-Brown, cult immortality with Deep End followed. Music by Harry Robertson.
[This has been released as part of the London Tales DVD, a three films on one disc bargain of C.F.F. works from the B.F.I.]