Well, I wasn't expecting such a response, thanks very much to you all.
Judith, yes, I do have Mary's death, and marriage to Lewis Whittle. She was 19 at the time and on the certificate is written "The consent of Henry Whittle the father of the Bridegroom and of John E Browne guardian of the Bride was given to the Minister." John E Browne being the younger of the brothers.
The family seems to be using the name "Brown" until 1871, but by 1881 have "Sarah Browne" on the funeral notice.
Cando, I do believe that's the right birth for Mary although I haven't got the certificate yet as they're so expensive here.
JM, I'm not entirely certain where Sheriff's Gardens is today. There was an article in the SMH in 1912 about "Old Sydney" (
http://trove.nla.gov.au/ndp/del/article/15374157?searchTerm=%22sheriff%27s%20gardens%22%20commonwealth%20street&searchLimits=) and I've found what might be the right streets in Surrey Hills.
I hadn't yet come across that SMH article from Sarah Brown, so thanks very much for that. I don't have John's death certificate, I'm debating whether that or Mary's birth certificate would be more useful.
Merlin, those do appear to be the right burials, I think I might try contacting the church history group to see if there's anything else to find out there.
Ros, thanks so much for pointing out that probate, I've been looking through the newspaper archives for a long time but never managed to find that.
Going off "formerly of Lochinvar", I found a newspaper article (
http://trove.nla.gov.au/ndp/del/article/18714885?searchTerm=%22sheriff%27s%20gardens%22%20brown&searchLimits=) which mentions at the end a Mr John Brown, station-master at Lochinvar, I suppose this must be him. Rather strangely he appears to be trying to have his father declared insane! If this is the right John Brown he seems to have immigrated to Australia, rather than being born here, and his father must be Thomas Brown who was attached to the Sheriff's Office, which explains the acquaintance with John Phelan.
Judith, yes, that certainly matches the dates I have for Sarah Jane, although there's another John Browne resident nearby in Singleton which makes looking at the BMD records a little difficult.
Sue, I'm rather perplexed by all those brothers-in-law. Lewis Whittle is Mary's husband, but Sarah Jane only married Julius Gerahty in 1887 several years later, so I wonder who Frederick Williams and Robert Formby are?
Thanks again for all your help, I'll have to chase up this Lochinvar connection now.