Henry was born in London on 13 September 1797 to Jackson Mortimer and Elizabeth Vaughan, and married Mary Addis in September 1819 in Hereford. He arrived in Hobart with Mary and their sons Matthew Henry and Mark William in 1825 Their daughter Mary Ann died during the voyage. Eight more children were born between 1825 and 1841. According to family memory, one reason Henry moved to the far-flung colony was the advice of his doctor to relocate to a place with a warmer climate for the sake of his health.
Two years after their arrival in Tasmania, when Henry was away from home, nine bushrangers came to their house. Mary was sitting with a baby on her knee when the men entered through the door and windows so that there was no escape. Threatening with a pistol they demanded jewellery, men's clothing and drink, of which there was none visible (the keg of home-made beer was in the cellar with the trapdoor covered by a carpet). After ransacking the house they left with their booty, and just when Mary had the kettle boiling one returned to take it from her, saying, 'It's full of water, just what I want'.
After this incident Henry taught Mary to shoot and she became quite expert at it. As a future precaution she buried the remaining jewellery under a tree near the house, but could never find it again. Eventually the men were caught and eight were hung. The ninth was saved when it was proved that he refused to shoot someone. The family moved to a two-storey house at Battery Point about twelve months later, but they would frequently return to the farm in one of their two yachts, the Richmond Packet and the Cockle Shell. In Hobart ,the children went to a day school with the children of Henry's sister Charlotte Selina and her husband Alexander Bishop Butler. One day Mary went to the door for a delivery of bread and there encountered the ninth bandit, now doing honest work.
From his time in Hobart, Henry appears on the Tasmanian Colonial Index as an employer of convicts between the years 1825 and 1835; as a witness at a trial in Richmond in 1833; and on the Jury lists from 1835 to 1840. His land grants from 1831 to 1833 were 1000 acres at York (Sandford) and 500 acres at Ralph's Bay Parish.
In 1839 Henry organised for his family and that of his sister, Charlotte, to leave Tasmania on the brig Caroline, which was also carrying timber for their homes in Melbourne. On the way the ship was driven ashore on Swan Reef where it was unloaded, salvaged, and allowed to resume the voyage without the timber, arriving in Port Phillip on Monday 16 December 1839. Henry had intended to leave his wife and children with his nephew John Blanch and his wife Sara. However, the next day two young men, Henry Griffin and Charles Deering, newly arrived in town, wandered into John Blanch's gunmaker's shop to purchase caps for their guns. One of them imprudently fired his gun forgetting that it was loaded. The result was an explosion which demolished the two-storey building and killed the young couple, John and Sara. Henry Griffin also died, but Charles Deering survived. Henry took the three Blanch children, who had been out walking with their nurse, to stay with his family.
Henry and the boys had been in town for a week or so and had pitched their first tents on the south side of the river just below what is now Queens Bridge. During a flood their boxes were carried out into the bay, causing them to move to the other side of the river to where the Customs House now stands. Although Henry could not get a room for his own family he managed to find a new stable for his sister and her children. After a month a room was rented for Mary and baby Edmund until a small place near King Street was purchased. When more timber arrived a cottage was commenced in Flinders Lane between Queen and Market streets and the family was thankful to move in. The Blanch children stayed until March 1841 when Henry advertised for someone who was leaving for England to take charge of 'two stout and healthy boys of the ages of 5 and 7'. A handsome reward was offered by Henry to anyone who was willing to escort the lads; he was sending his orphaned great-nephews, John and William, back to England to be with their grandparents. Later Henry built a two-storey house at the corner of Collins and William streets, where the family stayed for several years. It was here that his son Matthew Henry died of fever in 1841. Henry had a barque Favourite built on the Tamar River in Launceston, intending to take the family to England. He sold his property and they began the journey, firstly to see Sydney. Loath to let the ship sit idle whilst the family were enjoying themselves on shore, however, he sent her to Newcastle for a load of coal, but she stuck on a bar and did not return for six weeks. By this time Henry had decided that it would be too cold in England for him, and the family returned to Melbourne and 'Cranley Cottage' in Brighton. Henry later took the boys on a trip to California and when they returned the whole family went to Tahiti where they entertained Pomare IV, Queen of Tahiti, onboard the vessel. On their return from Tahiti, Henry gave the vessel to his son William (Mark William) who sailed first to Timor to buy ponies, and then on to Mauritius to sell the ponies, load up with sugar and return to Melbourne or Sydney.
In 1842 Henry stood as a candidate in the first Town Council elections in Melbourne. The election on 1 December 'was a wildly exciting and keenly contested one'. There were four wards, each with a polling booth in a local hotel. The polling for Lonsdale ward was held at the Royal Hotel in Collins Street and those elected were John Orr, Henry William Mortimer and John Pascoe Fawkner. On 9 December the Council met at the Royal Hotel and, behind closed doors, voted for a mayor and four aldermen. In a close election, Henry Condell was chosen as the first Mayor of Melbourne. Henry William Mortimer was one of two aldermen elected for a three-year term.
'Garryowen' reported in his Chronicles that Henry was 'intelligent and conscientious, but had a precise and pragmatical mannerism, which prevented him from becoming popular', and that he retired from the Corporation 'to take part in the management of the Patriot newspaper'. Henry was one the 'chief projectors' of the Victoria Fire and Marine Insurance Company when it was established in October 1848 with capital of £100 000 in 4000 £25 shares.
Henry was interested in church-building and collected a large sum towards the erection of the Baptist Church in Collins Street. Along with Robert Kerr and John Lush he also started the first school for Aborigines at Merri Creek in 1846. He 'had a good deal to do in the securing of Mr. Ham's [a Baptist Minister] valuable services, and though an Independent himself, Mr. Mortimer's energy and liberality on behalf of the early Baptists were as remarkable as creditable to him'. Henry and Mary Mortimer were accepted into the Independent Church, St Michael's Collins Street, on 4 February 1852.In 1863, when Dr John Dunmore Lang arrived in Melbourne, Henry 'in a few brief, stilted but suitable observations, officiated as the proxy of the ladies, and presented the guest with a minister's elaborately finished gown'.In 1864 he applied for the position of Deputy Registrar for Collingwood, using references supplied to him for his previous position, that of Inspector of Weights and Measures for the municipality of Fitzroy. In his application he said that 'I am an Old colonist of some twenty five years and can refer to most of the men of influence here to say that I have an unblemished character. I have made a considerable fortune but lost it by becoming security for others and in the depreciation of property. At present I am Inspector of Weights and Measures for Fitzroy but the income of £5.18.0 per quarter is too small to live on. If the two positions are incompatible I will gladly resign the former'.
Henry William Mortimer was listed as a new insolvent in 1861. The cause was given as his inability to meet his responsibilities and the depreciation in the value of freehold property. His liabilities were £13 394, his assets £16 995 and the surplus £3601.His testimonials show that he was greatly respected and was indeed of an irreproachable and unblemished character. His integrity, energy and general business habits, over a long period in the history of the colony, were remembered, and the first person to sign the testimonial was John Pascoe FawknerHenry died at the age of 90 in 1887. He was the last of the initial twelve councillors elected in 1842 who formed the Corporation of the City of Melbourne. His obituary records that he was among the earliest of the free settlers in Tasmania, having arrived there in 1825 with the inducement offered by the British Government of a grant of land under land warrants. Once he moved to Melbourne in 1839, 'he commenced a butcher's business, which he carried on successfully for many years, but his favourite pursuit was ship owning. He opened up a lucrative trade in fruit with the South Sea Islands, and subsequently he and his sons were the first to open the sugar trade between Melbourne and Mauritius'.
Unhappily the last years of Henry's life were clouded by loss of sight. He was blind for nearly fifteen years and was unable to participate in the active life to which he was accustomed. Yet he retained his mental powers until the last, dying on 21 July 1897 at the home of his son-in-law, Mr JR Brennand, JP, Toorak Road, South Yarra.