Oh God, OP, you're not wrong.
Always worked in education in one way or another, mainly in museums and galleries, so at the sharp end of every trend in ideology as you can imagine.
Incidents that stick in my mind:
Colleague saying with sinister intonation and narrowed eyes, after mention of children's traditional stories: "Hmm...and what do they mean by traditional, I wonder?" as if there was a risk the kids were going to be indoctrinated with Hitler Youth propaganda. God help us! I think Goldilocks and Cinderella was what she was referring to. (Yes, I know these tales were collected by German folklorists, the Grimms, but they have become part of British culture too.)
When in a training session about dance in primary schools, we saw videos of Indian, Irish, Scottish, Greek and other national dances. All good, and well-received by the trainees. The tutor concluded by saying 'That's some just of the possibilities, but you could also use English traditional dances such as May-pole dancing or Morris dances." Cue scornful snorting from a competitively right-on woman behind me, who couldn't believe this was a serious suggestion and said 'Isn't all that stuff really corny and outmoded?" Well...it might be, but I'm willing to bet that all the dances we'd just watched so earnestly from other cultures might well be their equivalent of Morris dancing!!! Had any trainees come from India or the other featured cultures, they might well have had a bit of a titter!!! But that's OK, because we only sneer at British stuff.
So very tiresome and silly. British culture is just as interesting as any other and I think we're pretty alone in dissing our own stuff in the way we do. Can't imagine the French doing that!