Here's what I know, plus what I've heard/read, plus what I suspect:
'Claybridge Sound Systems' originally started out (most likely in the early 60's) making PA systems out of Clayton (a suburb of Melbourne), Victoria, Australia. Builder, Ralph Bridges, then pivoted into making tube guitar amplifiers shortly afterwards. *As of now, no surviving amps or PA systems have surfaced from Claybridge, but there are multiple accounts of them existing from past owners and people involved in the company.
In 1966 (which we can infer from the above advertisement taken from the September 1966 edition of Go-Set magazine, and also a few of the components inside) he released his first fuzz pedal, a 3-silicon transistor (2N-3565) unit called the "Fuzzmaster". It came in a beautiful wedge enclosure with a green hammerite paint job and deep cherry red knobs. It's sound is closest to a Big Muff, but with the raw and unhinged nature of a MKI Tonebender. Circuit-wise, it shares characteristics with the Fuzzrite, but that's about where it ends.
Other than this, we know very little about it. As far as I have seen, only two units have ever surfaced. They came onto my radar around 2009, and I have been on the lookout ever since... Not one has popped up for sale in that time.