I didn't find much with the British newspaper research tools, but interesting facts and evidences for nose flute history.
The first mention I found is a classified ad recruiting two men for Humanatone demonstrations. Yes, Humanatones were apparently imported to Great Britain as soon as 1913!:
Liverpool Echo, Jan. 31, 1913:
In 1927, the Humanaphone, "all british make", was sold for 4 (old) pence and a half, as a Jazz instruent:
Hull Daily Mail, Oct. 3, 1927:
Was the Humanaphone a metal Humanatone copy, or a real Humanatone manufactured in Great Britain under license? What is sure is that it was the european nose flute the most similar to the american instrument. The differences with an early Humanatone look very tiny. Even the rivets and shape of the flap in which they are soldered are similar. Only the nose saddle edge looks a bit wider on the Humanaphone.
The North Devon Journal (05/25/1933) reported a Salvation Army musical festival, at the end of which the Captain Montgomery played his "Humanotone".
And finally, a 1938 Cheltenham advertisement selling nose flutes for an (old) sixpence the piece:
4½d in 1927 and 6d in 1938 represents a 33% increment in the price. We were surprised to notice a 25% augmentation between 1927 and 1936 in the price of the french Ocariflute (3FF to 4FF) [check the end of this post], but finally, the rise was comparable on the other side of the Channel.