Dalrymple was born in Scotland the tenth son of Sir Robert Dalrymple Horn Elphinstone, Bart., by his marriage with Graeme, daughter of Colonel David Hepburn.
In the mid 1840s, Dalrymple moved to the British colony of Ceylon where he became a coffeeplantation owner in the Central Provinces. Much of the land used for these British plantations was forcibly taken from local peasants, who were left both landless and unemployed as imported Tamilcoolies were used as labour. The displaced peasants revolted against the British in 1848 in what is known as the Matale rebellion. Dalrymple was a prominent plantation owner during this period and publicly defended the Governor of Ceylon, Lord Torrington, who was recalled due to his brutal crushing of the rebellion.
Exploration in Queensland
He arrived in Australia in 1857 and travelled to the Darling Downs hoping to acquire land. In 1859 he led an expedition to explore the Burdekin River catchment. This group included Ernest Henry, Philip Frederic Sellheim, Robert Phippen Stone and Richard Haughton which left Rockhampton to explore the Kennedy district. This district was in New South Wales when he left but part of Queensland, when he returned, having been declared a separate colony. Before his departure the New South Wales Government had proclaimed the districts of Kennedy and Mitchell for settlement, which was rescinded by the new Queensland Government. The party traveled west through the region and then north to the Valley of Lagoons, making surveys on the Burdekin and Suttor Rivers. These surveys were conducted to mark out promising runs for sheep. In 1860 he accompanied Lieutenant J. W. Smith and Robert Phippen Stone, on a voyage on the which examined many of the islands off the coast and discovered the O'Connell River, among other features. Stone Island, in Bowen Harbour, was named for R. P. Stone in recognition of his work in conducting soundings and surveys of the Bowen region. Dalrymple was part of the company that established the Valley of Lagoons Station in 1862 after the area was opened up by the government. A partnership formed between Walter Jervoise Scott, his brother Arthur, Dalrymple and Robert Herbert financed the acquisition of the leasehold. The partnership became Scott Bros, Dalrymple & Company with Dalrymple acting as manager. In October, 1871, Dalrymple was appointed Assistant Gold Commissioner for the Gilbert Ranges, and was also Police Magistrate for Western Creek, in the Bourke District. But the gold-field shortly afterwards collapsed. Then the Government asked him to mark a road from Cardwell over the Main Range. This he succeeded in doing, but from the exposure to which he was then subjected he contracted an illness from which he never completely recovered, and which eventually led to his death. On 9 September 1873, he departed on his final expedition to explore the north-east coast from Cardwell to the Endeavour River, accompanied by Walter Hill, Curator of the Botanic Gardens, also by Sub-inspector Johnstone, and others. It was on this trip that the Johnstone, the Mossman, and the Daintree Rivers were explored, and the rich and extensive alluvial lands of the Johnstone were then first discovered. Dalrymple became very ill on this expedition, and was granted leave of absence for some months after his return. Having partially recovered, he was sent to Somerset as Government Resident, but became dangerously ill after two months, and would have died at that time had not the Torres Straits mail steamer taken him away and given him the benefit of medical attention. His illness, however, was of a protracted nature, and the Government gave him a year's leave of absence, on full pay, to enable him to visit England, in the hope of the trip restoring him again to health; but it failed to produce in him any permanent benefit, and he was never well enough to return to the colony.
Having spent about two years in England trying to recover from his illness, Dalrymple died in St. Leonards, Sussex, England and is buried in Hastings Cemetery.
