Maybe after World War II? American servicemen shipped and brought back zillions of those tea sets, which were manufactured in post war war 2 Japan. My uncle sent sets to my grandmother, his sisters, and my mother. The lids all featured the same decorative knob or grip on the top that yours has, and each set has the same sort of scenic decoration as yours. My mother's had chrysanthemums, my grandmother's had Evergreens in front of a mountain, and I can't remember what the others had. If you hold the cups against the light and look into the bottom, you may see the image of a Geisha. Wish I had that set today!

If it were made in the years just after WW II it would be marked made in Occupied Japan.
I can't read the mark on the bottom, and of course the McKinley Tariff Act doesn't apply to Britain.
The style looks very like what we would call "Nippon"; ware made around 1890 to maybe 1920 and often marked "Nippon" which if Japanese for Japan.

Never knew that the new sets had an older precedent. Good to know!