The Constant was fitted at Deptford for convicts at the end of March and beginning of April 1843.
On the 12th April a detachment of the 99th regiment were received on board.
The Guard consisted of Lieutenant L.R. Elliott, Ensign George Jean de Winton, 52 Rank and File of the 99th regiment with six women and 9 children.(3)
In 1898 George de Winton published Soldiering Fifty Years Ago - Australia in the Forties in which he devotes a chapter to the voyage of the Constant in 1843 and describes his journey from Chatham to Deptford and then on to Kingstown.........
My time for foreign service came in April 1843, and, to the tune of the 'Girl I left behind me' early one morning we marched out of Chatham, the detachment commanded by Lieutenant Elliot, who had come to us from another regiment, the order being to march to Gravesend, thence by lighter to Deptford to embark on board the barque 'Constant' for Kingstown (Dublin), to take in convicts for Hobart Town.
As we passed through the streets of Chatham we were accompanied by many of the fair sex, who seemed disinclined to be left behind, several keeping with us till the band parted from us at the outskirts of Strood. The 99th had then a detachment at Tilbury Fort, and Captain Smyly, who commanded it, met us at Gravesend, and obtaining Lieutenant Elliot's leave, took me to the Fort, there to dine and sleep, and to join my ship on the morrow.
Off Deptford we lay some days taking in stores, and pleasant are my memories of the kind hospitalities received from officers of the Deptford Dockyard, to whom Chatham friends had given me introductions. On April 14, 1843, we set sail for Kingstown, the date I recall from its being an anniversary of my natal day. At Kingstown, in the week that elapsed before we received our prison passengers, we passed a very pleasant time. Many visitors came on board to see the ship and the arrangements for the 'accommodation' of the convicts, and so numerous were the invitations we received that we realised to the full the characteristic hospitality of the Irish. 
The prisoners during this time were probably embarked on the Constant by lighters. This was usually a very unpleasant experience particularly in bad weather.
By the 3rd May all the male convicts had been embarked and on the 9th May as de Winton described it the Constant spread her sails to the wind and Erin's Isle sank gradually beneath the horizon.
The Constant was a barque of about 500 tons, owned and commanded by John Hemery, a Jersey man, about thirty years of age, every inch a sailor and a gentleman, and engaged to be married to a cousin of one of our officers, a beautiful girl, to judge from the portrait which hung in the captain's cabin. The surgeon-superintendent was John Stephen Hampton, R.N., later chief of the Convict Department in Van Diemen's Land (now Tasmania), and afterwards Governor of Western Australia. He had made many voyages as surgeon-superintendent, and stood high in esteem in the service.
Throughout the voyage the weather was very unfavourable with wet and cold conditions particularly in the last month. The surgeon was concerned for the health of the prisoners because of the bad weather and paid particular attention to cleanliness and having them on deck whenever possible. One of the men suffered greatly during the last ten days of his life because off the inclement weather, tremendous seas and gales of wind. The surgeon had not held out any hope for his recovery in any case as his constitution had completely broken down by a vicious course of living in haunts of debauchery. 
George de Winton described his own discomfort during a violent storm....
The incidents common to such voyages as ours occurred. The ' (the word is not lexicographic but expressive) in the Bay of Biscay I remember to this day. We were under close-reefed topsails, with a head-wind and a jumping sea. At eight bells, noon, Hampton, Elliot, and I were taking a glass of grog in the cabin, staying ourselves as best we could on the weather side, when the cuddy table broke away from its lashings and went bodily to leeward, wrecking all the glass and crashing into the bulkheads of the lee cabins, a green sea, shipped at the same time, completing the confusion. Had we been standing on the lee side of the cabin, in the language of Bret Harte, the future incidents of the voyage might have interested us no more. Contrary winds drove us out of our course, and we sighted the island of Fernando do Noronha, the Noronha Brazilian convict settlement, which has been described as the convict's Eden. 
SURGEON JOHN STEPHEN HAMPTON
John Hampton kept a medical journal from 12 April 1843 to 18 September 1843 during the voyage of the Constant from England to Van Diemen's Land.
One of the soldier's wives gave birth to a still born baby during the voyage and sixteen convicts were put on the sick list, three of whom died. The ship's crew remained healthy although a ship's boy fell from the top gallant yard fatally fracturing his skull. Thirty one soldiers and a child were put on the sick list, mostly for trifling illnesses. Seven had been found to have 'the itch' and were isolated from the rest and treated with sulphur. All the convicts were mustered and inspected in divisions on Sundays and Thursdays to see that each had on a clean shirt and was shaved and otherwise clean. Divine Service was regularly performed. Schools established and every means used to give employment both to the bodes and minds of the convicts.
According to the Surgeon, there was no occasion for any corporal punishment throughout the entire voyage although according to George de Winton in his memoirs convicts were severely punished for attempting mutiny.
They did not call at any ports or sight land save Fernando do St. Paul Noronha, and the islands of St. Paul and Amsterdam.
John Stephen Hampton was Governor of Western Australia from 1862 to 1868, John Stephen Hampton administered the colony in an arbitrary fashion and created unrest among the free settlers. Nevertheless, his handling of the convicts was good and his public works programme was of lasting value to the colony. Hampton was born in 1809 and entered the medical branch of the Navy. In 1843 he visited Tasmania as surgeon-super intendent of the convict ship Constant. In 1845 he again visited Tasmania, and this time reported adversely on the conditions under which convicts served in the colony. The following year he was appointed comptroller - general ofgeneral of convicts, a post in which he was effective but also coldblooded. In 1855, when the Tasmanian Legislative Council opened an inquiry into the conduct of the convict department, Hampton refused to give evidence on the grounds that the department was under Imperial, not local, control, and in this he was eventually upheld by the Privy Council. He was appointed Governor of Western Australia In 1861, reaching the colony in 1862. In 1868, when transportation to Western Australia ended, Hampton retired from office. He died in England the following year. - Canberra Times 12 October 1963
ARRIVAL AT HOBART
On August 26, after a passage of 110 days, we made Storm Bay, where the pilot came on board to pilot us up the river Derwent to Hobart Town. A thoughtful pilot, he brought with him a sack of potatoes, and instanter these were delivered to the cook, and of potatoes and salt we made a meal such as we had not for long enjoyed. Travellers in the luxurious floating palaces of these days, with electric light, fresh water in abundance, fresh meat and fresh vegetables daily, can hardly realise the conditions under which long voyages were made fifty years ago. And none but those who for months have seen naught but sea and sky can realise the enjoyment of again seeing green trees and verdure in its varied forms, notably a panorama of such veritable beauty as the course of the Derwent from the sea to Hobart Town presents.
They anchored off Hobart on 29th August...... At Hobart Town we remained for some days landing prisoners and stores. In those days sentences were wont to be modified to some extent by good conduct on the voyage out, a humane arrangement by which hope was given even to the ' lifer.' On the arrival of a convict ship, convict officers came on board, and every man was interrogated as to his past career ; and the astonishment of a convict was often provoked when he found that his interrogator knew as much of his past life as he did himself, unaware that his police record came out in the same ship as he did. The interrogatories were given in rapid succession : Age ? Trade ? First conviction ? Second, third, &c. ? Sometimes the convict would answer incorrectly or evasively, when he would be immediately brought to book, and place, date, and sentence given from record, and thereafter the convict would know that evasion was useless. As mechanics and artificers of every class were in much demand, those who had but a very superficial knowledge of a trade often forcibly acquired a title, a sort of brevet rank, hardly justified by their qualifications.
Q. Trade ? A. - Well, sir, I've worked a bit in a brick- field.
Q. Build a house ? A - Oh no, sir. Build a wall ? ....
and before an answer could come "Put him down a bricklayer". Next ! 
The convicts were disembarked the on 7th September before the Constant sailed for sailed for Sydney on the 9th with the Guard who were discharged to the public service on 21st September 1843. 
Leaving Hobart Town, a few days' sail brought us to Sydney, whence a small steamer conveyed us up the Parramatta river to Parramatta, where we joined the headquarters of the regiment.
NOTES AND LINKS
1). Convict Records
2). Lieutenant George Jean de Winton was stationed at Norfolk Island for three and a half years in two separate postings between 1848 and 1853. His wife was Fanny, daughter of Thomas White Melville Winder, one of the "Roses of the Hunter", and when they departed Norfolk Island forever in 1853 they left a child buried in the cemetery there. George de Winton arrived in Australian with the 99th regiment on the Constant in 1843 and served with detachments at Windsor, Newcastle, Port Macquarie, Port Curtis and Brisbane before being stationed at Norfolk Island. In his publication - Soldiering Fifty Years Ago: Australia in the Forties - George Jean de Winton described his voyage in 1850 from Norfolk Island to Hobart on the Eliza.
 Journal of John Stephen Hampton, Ancestry.com. UK Royal Navy Medical Journals, 1817-1857 . National Archives, Kew.
 De Winton, George Jean, Soldiering Fifty Years Ago: Australia in 'The Forties', 1898
 Colonial Times 5 September 1843