eBay
This Excelsior Sonorous Class A Tuba is silver plated, and according to the serial number and the research I have done, was made in 1923. If you know a lot about Hawkes and Son serial numbers, please let me know if you think this is definitely correct, the serial number is 46073.

The Tuba is British-made, in Denmark Street Piccadilly Circus to be precise, and is silver plated. It is quite large, measuring 75cm high, and with a bell diameter of 35cm. It is reasonably heavy, but could be worn with a neck strap for marching. 

The tuba is is in surprisingly good condition for its age, and actually plays very well, with good clear notes, and reasonably smooth valves. There are obviously lots of 'dings', and some wear to the silver-plate, but no major scratches or huge dents, or twisting of the bell. There is also only one two tiny spots of corrosion, which has been treated to stop it spreading. 

Note: The postage is expensive due to the size and weight of the item, and the fact it will be insured to the value. It does not come with a case (or mouthpiece), but it will be boxed carefully and secured in place during transit.