Around 1905 Frank Hurley, being a 20 years old and with some initial successes in photography, joined the firm of Henry Cave. This firm most likely was a publishing firm producing the usual range of stationary items as well as postcards.
There are conflicting stories about how he entered into the business. The most popular, and the most doubful, was that his father bought a share of the business for Frank. The suspicion is that this version is just another part of the history og Frank Hurley as documented by Frank himself later in life. Although it must alos be remembered that Mr Hurley Senior was in the publishing trade himself, being a senior figure with the NSW Government Printer, so he would have known Henry Cave.
The reality was more likely that Frank, with his father's encouragemnet and blessing, joined the firm as the main photographer. Cave and Hurley then jointly put their branding on the postcards.
The partnership did not last too long with Hurley going his own way and establishing his own reputation and style of postcards.
As for Henry Cave, his career after the Cave and Hurley is not documented. I suspect he produced his own postcards for a while using C. as his signature. Curiously the photographs seen to date indicate that he may have used the same stock photos, possibly those taken by Hurley. Note this is speculation.
There is a series that indicates that on one occasion, his C postcard were altered to become Star Photo postcards. So the questions become: Did he work for Star Photo? Did he sell photographs onto Star Photo? Was he in fact Star Photo?