The old show was frequently highly reactionary but it also did better than most shows when it came to challenging establishment, bourgeois ideology and/or imperialist assumptions.
This division is the ‘ethos’. Frequently reactionary but with a proportionately greater tendency to buck this trend.
The hero of the show is a white male with a professional title, a line in Edwardian clothing (which retains a formality despite veering between scruffy, dandified, bohemian, etc.) and who travels around in a symbol of the British state. The odd Jacobite aside, his companions are usually thoroughly respectable types.
So, even when he takes a moral line against exploitation, it can seem like the civilized Englishman taking it upon himself to explain ethics to the barbarians.
However, while it may be possible to characterise this as an “overall or originating ethos” (as a poster at Gallibase put it) it’s one that has also been challenged from within.
At the start of the classic series, the Doctor is adamant that he cannot and must not intervene in history… including the religious practices of the Aztecs, a people destroyed by imperialism.
Then again, in that very same story, we also get a dose of condescension towards the Aztecs, portraying them as generally backward (i.e. “Autloc is the extraordinary man here!”) and suggesting that their religious practices will shock Cortés into attacking them. ‘The Crusade’ attempts a very sincere portrayal of Arabs as human beings… but also includes orientalist stereotypes.
When the first Doctor intervenes in the future history of aliens, etc., he very often takes a stance that seems very anti-imperialist, i.e. in ‘The Sensorites’. But, again, in that same story, the aliens are presented as encoded Asian stereotypes, and the human infiltrators are driven mad by their exposure to an inscrutable alien culture… which is pure colonialist self-pity.
But you also have to consider that, in the kind of fiction from which Who springs, the scientist figure, the lone inventor, was an ambiguous and untrustworthy figure who could not always be relied upon to toe the line. In Wells’ The Time Machine, the Time Traveller (clearly a forerunner of the Doctor) is explaining time travel to a group of friends when one of them imagines jumping forward in time to collect massive interest on a long-term investment… “…to arrive in a society run on strictly communistic lines perhaps?” suggests the Time Traveller.
All the same, the Doctor often assumes the right to intervene, which can seem imperialistic… but, having said that, the Doctor’s right to intervene does itself become the subject of some uncertainty within the show itself, several times. The Doctor has to justify himself to the Time Lords, firstly by claiming that power must be used to help those in need (and this in a story that forecloses on an imperialistic interpretation of that remark by being a forthright condemnation of imperialism), then by claiming during his second trial that he usually waits for a request for help from a local authority figure!
Times change and there was a shift in political discourse between the eras of the old and new shows.…