What's a "stain" here ? A dark coating applied to oak in 1925 is quite
possibly a deliberate attempt to darken it, to comply with the then
fashionable "stockbroker jacobean" and a mistaken idea that furniture of
the period had always been near black.

Yes, when I referred to stained oak, I meant that the stain was an
intentional finish and it your description and opinion seems spot-on.

But however mistaken the cabinet maker's intentions were, I'd like to
return it to that finish as it matches other items made by the same
person at the same time.

At the moment, most of the surface is stained in that Jacobean colour,
but areas that get worn have acquired a more natural medium oak colour.


If you're after a darker (but not black) finish that evens up pale areas
of wear, consider ammonia fuming it.

Is that the sort of thing that an amateur can do with some expectation
of succeeding ?