ARRIVAL IN NEW SOUTH WALES
Henry Owen came to New South Wales on the Mariner which arrived from England via Hobart in August 1821.
His brother John Cranmer Owen was not listed as a passenger on that vessel although he was in Sydney as the brothers had established a merchant business together at 80 Pitt Street, Sydney by August. 
In a petition dated August 1822, Henry Dixon Owen recommended his servant Dennis O'Brien for a grant of land. His correspondence suggests that he had been in Australia for over six years and therefore may have joined the Mariner at Hobart......Dennis O'Brien has been in my confidential employ for six years and has been known for me upwards of seven and has been entrusted with property to a large amount - I have proved him most worthy, sober and industrious and respectfully recommend to your Excellency the prayer of this petitioner. This was Dennis O'Brien who arrived on the Three Bees in 1814 and had been granted a conditional pardon and was requesting a grant of land. 
Henry Owen was promised 1100 acres of land with an option to purchase a further 300 acres adjoining the estate in 1822.
In correspondence by the Colonial Secretary dated 28 June 1822, John Cranmer Owen was promised a grant of land in proportion to the number of convicts his means would enable him to take permanently off the stores and on his forwarding his letter of recommendation from Lord Bathurst that was in the hands of Lieut-Gov. Sorrell  This does not seem to have taken place.
In 1822 Henry Owen's assigned servant was given permission to proceed to Newcastle. In 1824 Owen sought permission to travel from Windsor to his farm with cattle and with his four government servants to be supplied from the government stores at Newcastle. These four men arrived on the Henry in August 1823:
1) James Johnson - Previously assigned to Alexander McLeod and brought cattle overland from Windsor for McLeod in 1823.
2) Richard French - Previously assigned to Alexander McLeod and brought cattle overland from Windsor for McLeod in 1823
3) John Clark
4) William Green - Previously assigned to Walter Buchanan Wilkinson and brought cattle overland from Windsor for Wilkinson in 1823
Michael Casey who arrived on the Mangles in 1822 was also assigned to Henry Owen in 1823/24.
In 1825 the following convicts are included on lists in the Colonial Secretary's Correspondence as assigned to Henry Owen at the Hunter River -
John Painter Arrived on the Speke in 1821. Aged 22. Native of Tewkesbury; 5'7 3/4"; dark eyes, flaxen hair, florid complexion. Absconded from service in December 1825
Thomas Holden Arrived on the Mary in 1822. Transported to Norfolk Island for life in 1838 for the murder of his wife Mary Sullivan.
PERMISSION TO CUT CEDAR
Later that year Henry Dixon Owen applied for permission to cut cedar and blue gum from his property and by 1826 had begun a house on the land which had remained unfinished for want of a carpenter. 
By 1828 he was in financial difficulty and calling for debts to be paid ...Notice - All persons having any demands against the late Firm of John and Henry Dixon Owen of this town, are respectfully requested to forward the same to the Office of his Solicitor. The Advertiser takes this public opportunity of requesting those persons who have been so long in the debt of the late Firm, that they do the needful forthwith the reciprocity of those friends has not been mutual, consequently they cannot, and must not expect the "Quid pro Quo"...Henry Dixon Owen, Hunter River.....Trespassers Beware, Aberglasslyn Hunters River - 14th August 1828 
SIR JOHN JAMIESON
In 1828 Henry Dixon's farm (Aberglasslyn) with a 'comfortable cottage' was auctioned by order of the Sheriff and purchased by Sir John Jamieson. .....The purchase was confirmed in 1833 - Title Deeds to Grants of Land - Purchase authorised by Sir Thomas Brisbane by Sir John Jamison, 300 acres at Maitland being the quantity originally authorised for Henry Dixon Owen. 
Convict John Nowlan who arrived on the Marquis of Huntley in 1828 was first assigned to Henry Owen probably straight from the ship. When the 1828 census was taken in November 1828 he was recorded as an assigned servant of Sir John Jamieson. Joel Richards who arrived on the Marquis of Hastings in 1826 was assigned in 1828 and remained there after he received his ticket of leave in 1834.
A.C.F. Smith was employed as Superintendent in 1828
Sir John Jamieson later leased the estate out for a time and then in 1836 sold it to George Hobler who built Aberglasslyn House.
After leaving the Hunter Valley Henry Dixon Owen became a squatter on the Western Plains. His brother John returned to England. 
From across the river, Aberglasslyn House, Aberglasslyn, NSW, Australia - March 24, 1961 - Cultural Collections, University of Newcastle
. Ancestry.com. New South Wales, Australia, Colonial Secretary's Papers, 1788-1825Series: (NRS 937) Copies of letters sent within the Colony, 1814-1825 Item: 4/3506 Page: 2
 The Sydney Monitor 23 August 1828
 Sydney Gazette 15 August 1833
 Ancestry.com. New South Wales, Australia, Colonial Secretary's Papers, 1788-1825 (NRS 900) Petitions to the Governor from convicts for mitigations of sentences Item: 4/1866 Page: 120d
 Sydney Gazette 14 August 1822
 Wood, W. Allan., Dawn in the valley : the story of settlement in the Hunter River Valley to 1833 Sydney : Wentworth Books, 1972., p.26