This magnificent bakelite loadspeaker is a relic of the early days of radio and audio. I have no way at present to assess its function but it is in excellent condition as the pictures attest. The bakelite is lusterous and this displays nicely.
I have found nothing on the British Thomson-Houston Co. (BTH) loudspeakers on the internet. The design is similar to Atwater-Kent and Philips loudspeakers of the era.