He was appointed assistant government surveyor under John Oxley in 1821, a position he held until 1827, surveying among other places, the township of Newcastle in 1822. He worked hard in the colony; a colonial surveyor's work was arduous to the extent that their health was often impacted. He left a lasting legacy for Newcastle and the Hunter Valley, not only because of his survey work and places named in his family's honour but because of his later public contribution and vision for the colony. He gave his time and enthusiasm for the advancement of the Hunter Valley, being both a government councillor and magistrate. The Australian Dictionary of Biography lists his many occupations: explorer, grazier, immigration promoter, Member of Upper House, public servant and surveyor. 
He received two grants of land for his services as a surveyor - 300 acres he named Neotsfield and another of 700 acres.
The only convicts found so far assigned to him in the early days at Newcastle were Patrick Mulligan in 1822 (ship Isabella), David Jones in 1823 (ship Lord Sidmouth) and John Davis in 1824 (ship Sir William Bensley).
Return to England
He returned to England in 1827 leaving his estates in the hands of his brother William Dangar. His return to England was to appeal against a decision to suspend him from position of surveyor and deny his claim for 1300 acres, pending investigation into charges that he had appropriated to himself and family upwards of 7000 acres.
While on his way to England he wrote a Directory as an intended Guide to Settlers. The directory can be found online at the University of Newcastle Cultural Collections and the Map at the National Library of Australia site. The engraving below A View of King's Town was included in the directory. Click to enlarge.....
The Australian newspaper gave the following account in September 1828:
Mr. Henry Dangar, who was not long ago an Assistant in the Surveying Department, has, we find, compiled his map of the river Hunter, with its tributary streams. We have not seen the map as yet - and are rather disposed to believe, that a copy of it has not as yet reached the colony.
The map was to be published by J. Cross, 18 Holborn, opposite Furnival's Inn, London, on a scale of three miles to an inch, including a plan of King's Town - the new name by which Newcastle has been christened, and dedicated by permission to his Excellency Lieutenant General Sir Thomas Brisbane, K.C.B., late governor in chief of the colony. - a compliment which can scarcely fail of being as gratifyingly received as it is judiciously applied. In the map were also to be described the position and extent of lands appropriated to Crown purposes; the lands located to settlers up to the month of August last year - the land remaining unappropriated at that time, in the Hunter's river district, as well as that of the adjoining important country - Liverpool Plains, and that on the North bank of the Manning river. It was also to include the harbour of Port Stephens, with the rivers falling into that part, and the grant of the Agricultural company, to be accompanied by a copious book index and directory, shewing the conditions upon which the grants of land are held, with accurate and particular descriptions of the unappropriated country - the terms upon which land is understood to be granted by government and other information likely to prove useful to persons disposed to emigrate.
The Directory and Map eventually reached Australia in March 1829 and could be purchased for 5 guineas. It was described in The Australian as:
A most splendid work accompanied by a book of reference describing every individual's farm, its character and quantity and the nature of the tenure, whether free grant or purchase. The principle defect is that numerous additions since Mr. Dangars' departure from the Colony are of course omitted from the map.
Despite this defect, the Directory was a valuable resource for those intending to emigrate. The accompanying Map of the Valley, and Newcastle Town had great detail of rivers, landmarks, towns, land use and topography. The Directory is a who's who of land owners and lease holders at that time. The Directory contributes a great deal of knowledge of Newcastle and the Valley as it was in the 1820's, the best that had been produced to that time. They must be among the most important documents of the early history of the Hunter Valley. Although many landmarks on the map were given European names by Henry Dangar, there are also Aboriginal Place Names recorded which otherwise may never have been known - Purandarra Brook, Bundangbing Brook, Kolen Kolen, to name a few.
Return to Australia
When Henry Dangar returned to Australia his new wife Grace Sibly accompanied him. Grace Sibly was the elder sister of Margaret Sibly who later married surveyor Robert Dixon.
Henry and Grace were eventually to have five sons and two daughters together - William John, Henry Carey, Frederick Holkham, Albert Augustus, Francis Richard, Margaret Elizabeth and Florence Blanch.
He was embroiled in controversy in 1838 after the massacre of aborigines at Myall Creek by stock keepers and convicts and the subsequent execution of the perpetrators. This event is covered extensively elsewhere.
Meat Canning Factory
In 1848 Henry Dangar together with his brothers Richard Dangar and William Dangar began a meat canning factory at Honeysuckle Point, Newcastle.
There can be no doubt that a most important trade, that of preparing fresh meat for exportation is gradually springing up. A very large establishment belonging to Mr. Henry Dangar has just been completed at Newcastle and commenced operations yesterday. With some of the Finest and cheapest meat in the world, there can be no reason why this trade should not increase until preserved meats are looked upon as one of the staple exports of the colony .
The Newcastle Meat Preserving Company had been established after the Depression and drought of the forties caused a decline in cattle and sheep prices. Although the business won awards at the Great Exhibition of 1851 and exported their product to India and California, the company had ceased to operate by 1855.
From 1846 to 1851 Henry Dangar was a Member of the Legislative Assembly. In 1847 he entertained the Governor Sir Charles Fitzroy at Neotsfield, providing refreshments before the party moved on to Singleton. Later that evening at a dinner for the elite of the township he was rebuked by the Governor when he attempted to introduce politics into the conversation .
In his candidacy for the Northumberland county in 1848....
Dangar has shown that he is one of those who are prepared to uphold the pecuniary interests of the woolgrower and the employer of labour at any sacrifice; he is for the resumption of transportation in any shape - either the old or the new, and has no objection to the importation of cannibals or coolies, providing that a profit can be extracted out of their labour. He has however always expressed an anxiety for free British labour; and is one of those who only side with Dr. Bland when the Dr.'s crotchet can be made available for procuring an additional supply of labour. As a squatter he is one of the ultras, though we must do Mr. Dangar the justice to say that we believe he is desirous of seeing a reduction in the price of land. The electors of Northumberland may take it for granted, that on all questions in which the immediate interests of the squatters or of the employers of labour are at issue with those of general community Mr. Dangar will be found amongst the advocates of class interests. Apart from these interest Mr. Dangar has made a good useful member of Council. Unlike many of the country members he has been regular in his attendance and he has made a point more especially of being there when the estimates were under discussion, and has been a steady and independent advocate for economy and equally in the expenditure of the public money. His views on most practical questions are marked by good strong sense; and in matters affecting different religious communities he has shown a steady desire to carry out the spirit of Sir Richard Bourke Act. In the promotion of the district and local interest Mr. Dangar has been zealous and active.
Dangar extended his land holdings and by the 1850's his stations included:
Gostwyck 48,000 acres
Paradise Creek 32,000 acres -
Bald Hills 19,200 acres
Moonbi 25,000 acres
Bulleroi 64,000 acres
Karee 64,000 acres
Myall Creek 48,000 acres.
After retiring from public life, he sailed for England in 1852, however returned to N.S.W. in 1856, living at Potts Point, Sydney. He died on 2 March 1861, and was buried at Singleton, N.S.W. He was survived by his wife and 5 sons and 1 daughter.
2). An 1899 Article from the Newcastle Morning Herald......
A Newcastle Pioneer-Henry Dangar. (By OLD COLONIST.)
On less than the fingers of the two hands could be counted descendants of the early pioneers of the Hunter now owning land in the river basin granted to their forefathers. The Dangar family is an exception, as members of it still own valuable property. In Newcastle and up the Hunter River that was acquired by Henry Dangar in the early days.
Henry Dangar was descended from a French family that migrated to England during the time of one of the many French revolutions. His father, who was a farmer, bought and lived on a farm near Neots, a village in Cornwall, England. When a young man Henry Dangar and his brothers emigrated and landed in this colony some where about 1823 or 1824. Shortly after arrival Henry obtained employment from the then Governor as an assistant surveyor and was engaged for nearly six years in completing a survey of the Hunter River district. He laid out the City of Newcastle as viewed at the present time. In those days land could be obtained on the condition that a portion of the grant should be cultivated. In that way he secured seven hundred acres. The grant he named Neots field, now occupied by either one of his sons or grandsons. While Mr. Dangar was surveying that property he was chased several times by the aboriginals and had to run for his life.
After he obtained a title to his grant he visited England, and was absent from the colony for about five years. On his return he was employed by Sir Edward Parry, the then manager of the A.A. Co., For that company he took up that fine station Warrah, on the Liverpool Plains. He, after his return to Newcastle left the company's service, secured the services of some exiles, procured the necessary outfit, and ascended the Hunter River in a boat as far as Neotsfield, where he settled down and devoted himself to pastoral and agricultural pursuits.
Being of an adventurous spirit he fitted out and led an expedition to the north-west. He ascended the Northern Tableland near where Tamworth now stands, and penetrated north till be came upon the country on a portion of which Armidale now stands. Near to that city he took up a large and valuable tract of country, which he named Gostwyck, after his right-hand man, Gostwyck Cann. That property is still held by his descendants. From that point he struck out in a north-westerly direction and took up another large tract of country on Myall Creek, a tributary of the Gwydir.
Subsequently, after he had sent men and stock to occupy the country, the locality was the scene of a terrible massacre of the blacks, who at the time were hostile and dangerous. Further to the north they had attacked and killed seven white men who were engaged in forming a station for a Mr. Larnach. Partly for self-protection and partly for revenge, Mr. Dangar's men and some others, early pioneers, surrounded the blacks and drove a number of them, men, women, and children, into the stock yard on Myall Creek station. There it was alleged they were shot down and their bodies subsequently burnt on piles of wood drawn together for the purpose. By some means information of the massacre reached Mr. Plunkett the then Attorney-General. He at once issued warrants for the arrest of the perpetrators. Nine of them were arrested and conveyed to Sydney, where they were subsequently twice tried - the first time for the murder of a blackfellow, of which they were acquitted. The second trial was for the murder of a boy. - For that offence they were found guilty and afterwards hanged. Strenuous efforts were made by several of the early pioneers to procure a mitigation of the sentence but without avail.
At that time and previously no mercy had been shown to the blacks by the early settlers. As an example the law was allowed to take its course. Many who for several years afterwards had to contend against the cruel and cunning savages considered Mr. Plunkett's action unnecessarily severe, and in effect made the white men more relentless.
Mr. Dangar was elected as the representative of Northumberland in the first Legislative Council. In conjunction with Messrs. Wentworth, MacArthur, and others he espoused the unpopular side by supporting the policy of continuing the transporting of convicts to the colony. The agitation led to the total cessation of transportation.
He was the first in the colony who practically tested the tinning of meat as a remunerative industry. He established a factory for the purpose at Newcastle and made his mode of meat-preserving a success. But the heavy cost of labour and uncertainty of the market compelled him to close his works.
After spending twenty-five years of his life suffering the hardships attending pioneering, he visited England in '53, where he remained for three years. His health failing he returned to Sydney. After five years of continuous suffering he passed away on the 2nd of March 1861. A gentleman who was well acquainted with him wrote in his diary that Mr. Dangar was a favorable specimen of one of the early hardy pioneers, who seemed especially formed for the development of Australia. - He was neither specially gifted with Intellect nor means, but possessed strong common sense, resolution, and energy, and availed himself of the opportunities of the times. While contributing to the development of this grant country he gathered a fair share of worldly success, and has left behind worthy descendants to perpetuate his name. The name of Dangar is in inscribed on the plan of Newcastle and suburbs in many places. The Great Northern Hotel, the leading hotel in the coaly city, stands on land once his property, now owned by one of his descendants. Newcastle Morning Herald 8 June 1899