P.B.S. Wrey, 12th Baronet, son of Sir H.B.T. Wrey and his wife Marianne Sherard, was educated privately and from 1876 to 1879 served an apprenticeship as a civil and mining engineer with James Henderson of Truro, Cornwall. He then came to the Cape Colony, working as a mining engineer in Kimberley during 1880-1881. In 1883 he passed the Survey Certificate examination of the University of the Cape of Good Hope. From 1883 to 1885 he was employed by the Cape government to survey and report on the Walfish Bay territory, though he was admitted as a land surveyor only in the latter year. The map of the bay and adjacent territory resulting from his survey was completed in December 1885. In 1889 he reported to the Colonial Secretary (London) on the Walfish Bay boundary question. That same year he married Alice M. Borton, with whom he had two daughters.
After working as a mining engineer in Johannesburg during 1886-1891 Wrey went to Rhodesia (now Zimbabwe) as consulting engineer to the Mashonaland Agency and its subsidiaries. He held this position until 1899, when he became general manager of the group. He was president of the Rhodesia Chamber of Mines for 1901/2 and resided in Bulawayo.
Wrey became a member of the Rhodesia Scientific Association in 1899, the year of its formation, and served on its council for 1907/8. In June 1907 he read a paper on "Tree culture in Southern Rhodesia", which was published in the association's Proceedings (Vol. 7(1), pp. 71-94). The paper included brief descriptions of trees suitable for cultivation, their characteristics and uses. He was still a member of the association in 1931.
During his early years in Zimbabwe Wrey contributed two chapters, one on the prospects of Mashonaland and the other on the causes of the war with the Matabele, to The downfall of Lobengula: The cause, history and effect of the Matabeli War... (1894), by W.A. Wills and L.T. Collingridge.