David Thomson first came to New South Wales as Surgeon Superintendent on the Prince Regent arriving on 7th August 1824.
The Prince Regent departed London 28th February 1824 and called at Bahia before landing in Van Diemen's Land and then on to Sydney. Passengers included William Carter Esq., Mrs. Carter and Miss Carter; J. Stephen, Esq., Mrs. Stephen, Miss Stephen, Mis M.A. Stephen, Miss C. Stephen, Master Stephen, Master G. Stephen, Gregory Blaxland, Eaq., A. McLeod, Esq., N. Lawson, Mr. and Mrs. Carlisle, Mr. and Mrs. and Miss Ward, Mr. H. Stuckey and Mrs. H. Slade, all from England. 
David Thomson had not been intending to remain in the colony however changed his mind when he arrived and in a Memorial dated 10th August 1824, applied for a grant of land.....
Having lately arrived in this colony and it being my wish to remain as a letter I have to request you will be pleased to direct that the usual allowance of a Grant of land proportionate to my ability to cultivate the land may be made me.
I came out here as Surgeon of the ship Prince Regent and it not being my intention when I left England to remain abroad, I did not apply to the Secretary of State for the Letter usually granted to Settlers.
With respect to my means, I beg to state that I only brought with me what I considered necessary for my expenditure during the voyage amounting to two hundred pounds in cash. That so soon as returns can be had from England I shall receive three hundred pounds in addition to which I receive half pay as a Surgeon of the royal Navy amounting to one hundred pounds a year. I therefore trust that you may be pleased to take these circumstances into consideration and direct that the allowance of a portion of land may be granted me. 
In December he was advised that 1000 acres of land in Sections eight and fourteen of Township twenty eight in the neighbourhood of Hunters River had been reserved for him for eighteen months.
Employment in the Colony
In correspondence dated 30 August 1824 he revealed his previous service and qualifications when he applied for a situation in the Medical Establishment of the Colony:
Having arrived in this colony and it being my intention to remain, I beg leave to offer myself a candidate for any situation on the Medical Establishment that may now be vacant, or in future may become so.
With refernce to my professional qualification, I have to state that I have obtained Diplomas from the College of Surgeons of Edinburgh and of London. That from the year 1807 til 1814 I served in the Royal Navy. The five last years of that period as full Surgeon and that I have Certificates of character and ability from the different Captains under whom I served.
If I should be so fortunate as to obtain an appointment to any situation in this colony it shall be my constant endeavour to discharge its duties with care and attention.
David Thomson was employed as surgeon superintendent four convict ship voyages to Australia:
4). New Grove in 1835 (VDL) - On the voyage of the New Grove David Thomson took over duties of Surgeon Superintendent at Scilly, in consequence of the surgeon George Rowe having become dangerously ill. When David Thomson arrived on board on 24th November 1834 there were one hundred and sixty five female prisoners, five free women and twenty eight children.
Emigrant ship John Barry
He was Surgeon Superintendent on the emigrant ship John Barry 1837. He gave evidence in parliament regarding the voyage of the John Barry. .....
Thursday, 27 July 1837. Statement, transmitted from the Quarantine Station, by David Thompson, Esq., R. N., Surgeon Superintendent of the Ship 'John Barry,' with Emigrants from Scotland, in reply to questions from the Committee.
I am not aware to what extent useful emigrants to these colonies can be procured from Dundee, and other ports in Scotland; but I am of opinion that the port of Leith or of Glasgow would, either of them, be preferable to Dundee, as I think the emigrants would be sooner collected, and from a superior class of mechanics.
Of the persons embarked at Dundee, there were 79 married couples, three single men and eight single women, and 150 children of all ages.
Three adults have died, one of fever, occasioned by exposure to the hot sun at St. Jago, one of malignant scarlet fever, and lately one of typhus. Twenty-three children have died of various diseases, but mostly of affections of the bowels, arising from unsuitable food. The number of deaths is certainly greater than would likely have taken place had they remained in their native country. The tonnage of the ship is 624 tons; she is an old ship, not particularly leaky, but admitted water both by leakage and down the hatchways, during the run from the Cape of Good Hope to Port Jackson, the weather having been generally boisterous. She was the reverse of comfortable in her 'tween decks, being encumbered with luggage to such a degree, that in bad weather, when most persons were below, it was difficult to pass from one end of the ship to the other.
The provisions and water were wholesome, and served in sufficient quantities. I had the usual medical comforts supplied to convict ships. The allowance of a pint of porter daily to women suckling would certainly be conducive to their health, and that or their infants; but I consider the most dangerous period for young children to be that between the time of weaning and their attaining about the age of three years. The allowance to these latter of half a pint of preserved milk daily, would, I am of opinion, save many lives. While the weather was warm the 'tween decks were frequently washed, being the mode of cleaning to which the emigrants had been accustomed. The decks were in general scraped and sanded; to assist the operation of scraping, a little sprinkling was necessary, the deck being almost always in a dirty state, from the inveterate habit of the emigrants of throwing all kinds of rubbish, refuse victuals, etc., at their feet on the deck, which, therefore, never remained long in a clean state. The emigrants were almost invariably quiet and orderly. All disputes between individuals were referred to a committee of their own number, elected by themselves; few instances occurred of their interference being required.
I had no other ground of complaint than their inattention to cleanliness. An insurmountable difficulty, in preserving due cleanliness and ventilation, arose from the enormous quantity of luggage they were permitted to bring on board, the whole of which was stowed between decks. Emigrants ought to be restricted, both in the number and dimensions of the chests or packages they bring with them, and this regulation should be most rigorously enforced. I feel a difficulty in suggesting any measures that would give the surgeon-superintendent useful authority in enforcing cleanliness. The circumstance of their being allowed a free passage appears to create in them a feeling of their own importance, and consequent unwillingness to be directed or advised. It would certainly be preferable that the emigrants should come out under the charge of the agent who selected them, as they would, in that case, be more likely to comply with those terms which they had been previously told would be enforced, than in charge of a stranger who had no acquaintance with them previous to embarkation. The 'tween decks were frequently sprinkled with chloride of lime in solution; but not whitewashed, as this could not be done without soiling the bed-places and clothes of the emigrants; neither was there on board whiting for the purpose. The hanging stoves were frequently used, but less advantageously, on account of the luggage in the 'tween decks. Sand and scrapers were generally used in cleaning the decks and berths. - Parliamentary Papers
David Thomson resided in Raymond Terrace in 1841 however by 1843 had moved to 'Pentland' at Murrurundi where he was appointed Magistrate.
In 1848 he decided to leave the district and his household furniture and other household goods were advertised for Auction. The auction was held on the 14th July 1848 after the Page's River Races.
David Thomson returned to England, and although he died in Guernsey in 1874, his estate near Murrurundi was still known as Dr. Thomson's Pentlands fifteen years later.