From 1979: THE TOMORROW PEOPLE novelization of HITLER'S LAST SECRET.
FILE UNDER: You wouldn't see the likes of this on the CBBC Channel today.
It's an adaptation of three serials (totaling six episodes) from the original series' sixth season, transmitted in 1978.
TTP is a wildly inconsistent series (whereas the most recent revival was just consistently underwhelming) but the Hitler-thon is one of the standout stories. You have to admire the sheer cheek of Thames and ITV to offer up Nazis (and regular cast members dressing as Nazis as part of the latest teen fashion craze) as part of the tea time schedules (although, tellingly, this doesn't seem to have evoked any criticism from audiences or within the fractured ITV network) and then revealing (here comes the secret) that Hitler was actually a cheap and cheerful alien cobbled together by the Teddington effects team. The fact that he's played (not for the last time) by 1980s Grange Hill villain Mr Bronson, aka Michael Sheard, just adds to the fun. It also features a young Nicholas Lyndhurst as a Nazi soldier and (for the series) surprisingly good production values with a fair chunk of location recording.
The Reich was hardly unknown to kids friendly time slots thanks to multiple WWII padding out the afternoon schedules to give the continuity announcer time for an extended coffee break, chat with his mates and run another business on the side. But appearances in actual Kid Vid was rarer. GALACTICA 1980's pilot outing transported the Next Gen Colonial Warriors (and Jamie) back to occupied Europe on the hunt for Richard Lynch but that was a family hour show (although pitched largely at kids) and just an excuse for the cash-strapped quickie to raid Universal's costume store.
I don't remember seeing the other two stories adapted (time to unearth that DVD box set again) but The Thargon Menace certainly sounds topical today. Maybe that's the version of the show they should have revived for modern times.