Ho Hum............. boooriiiing
Hi Paul,
As far as I can ascertain that is the Lightning Brace made by the Hamden Mfg Co of Wallingford Connecticut USA, possibly from about 1905. I have one of these and it's got "patent applied for. 102" stamped on it. It is slightly different from the one in your photo, where the base of the chuck and the wedge both appear to have three flat facets on the upper surface mine is uniformly round.
I don't know if these were ever sold here, mine came from the US.
It works quite well, the harder you lean on it, the tighter the wedge collar grips the tang of the bit.
Thanks for posting, I had wondered which one I would obsess about today, and 'ol Lightnin' hasn't been obsessed about for some time.
Cheers,
Geoff.