Re John BROWNE and Lochinvar in NSW
http://library.sl.nsw.gov.au/search/X?lochinvar&searchscope=2 NSW SL catalogue gives Lochinvar as on land that is part of an original 2000 acre land grant to Leslie Duguid in 1823. Near to or adjoined to W C Wentworth’s Luskintyre and Mrs Harper’s farm Windemere and an advert in the Australian March 19, 1840. Trove has many of the adverts which ran in all the leading newspapers. Here’s one link ….
http://trove.nla.gov.au/ndp/del/article/2537408 Sydney Gaz 28 March 1840.
NSW SRO has Lesslie DUGUID land at reel 1121. There was a Court of Claims re the Duguid land in March 1834. First Possessor of Land listed as William Longford. Reel 1420
NSW ER 1870 THE HUNTER
John S BROWN, freehold, Lochinvar
NSW ER 1878 THE HUNTER
John S BROWN, freehold, Lochinvar
Walter William BROWN, residence, Lochinvar
Alfred C BROWN, residence, Lochinvar
As John BROWN/e died in Sydney in 1871, the two entries above are NOT him.
BUT

There is a John BROWNE listed at Sheet 2 of the Parish Map of Maitland, County of Northumberland, barcode 158386 on the lpi website
John BROWNE 5 April 1836
Portion 166 and 167
Plan 188 663 and 217 663
Location diag
Vol, Folio (or Date) 5.4.1836
Area 1.341 (for 166) and 2.175 (for 167)
Purchaser for both 166 and 167 John Browne. On 167 “see note ( 8 ) "
So on that part of that sheet 2, the notes are on the right hand side and Note 8 reads
Resumed for Recreation. Gaz 16th January 1951, 5217ms Ms 5395 3070 R So Portion 167 may well be a sporting oval or similar even today

I realise that John BROWNE died 1871, and the newspapers have him as aged 47, and it would be unusual for a 12 year old to purchase land in NSW in1836, however I think it is worthwhile following up to see who the person was who did purchase that land in 1836. The NSW SRO records should give the name of the ship of arrival for the purchaser. And if the purchaser was born in the colony, that would likely be stated in those CSreLand records too.
NSW SRO CSreLand index has just the ONE John BROWNE listing purchasing land in 1836. It is on reel 1103.
http://srwww.records.nsw.gov.au/indexes/searchform.aspx?id=14&new=1Leaving it up to our OP to get to the original records to see if this is the right family

perhaps a generation earlier.
Cheers, JM