Begg was born in Montrose, Scotland, was apprenticed as ship's carpenter and served as a seaman for several years before around 1840 being put in charge of a cargo boat shipping timber from the Baltic. In 1855 he was appointed captain of the Sebastian on the India route, calling in at Adelaide and Mauritius on the return voyage. His next appointment was as captain of the Orient Line clipper Coonatto trading between England and Adelaide from 1863 to 1866, when he was put in charge of The Murray, on which he served until 1872, making very good voyages, and impressing his passengers with his urbanity and sailor-like qualities, an asset to the reputation and no doubt profitability of the Orient Line. He settled in Adelaide and was made manager of the Tug Company, then was appointed ship's surveyor for Lloyd's of London. In 1877 he and John Legoe had a part in formation of the Port Stevedoring Company, and he served with that company until a few weeks before his death.
Recognition
Begg was awarded a silver medal by the Italian government for his part in rescuing sailors from a burning vessel. This was the Mannin Barabino, which caught fire while sailing from Genoa to Puerto Rico in May 1870. Begg and the crew of The Murray went to her aid and did what they could to rescue survivors, but 120 perished either in the inferno, the barque's cargo being largely spirits, or in the sea after her overloaded boat capsized.
Family
Begg was married twice; by his first wife he had three children:
Robert Caithness Begg, master of the barque Pakwan 1875–1878 married Eliza Allsop, youngest daughter of Captain Allsop on 19 November 1873.
Elizabeth Begg married John Fletcher on 23 December 1875. John was son of slipmaster Henry C. Fletcher.
Helen Wylie Caithness "Nellie" Begg married George Wafford Dempster on 3 December 1878
He married again, to Eleanor Allsop, daughter of Captain Allsop. They had seven children, including:
William John Allsop Begg married Ada Haussen on 3 March 1888. She was a step-daughter of F. E. Bucknall.
Henry Allsop Begg married Agnes Augusta Parr Hanson on 16 October 1891
Percy William Begg born London
Charles Murray Begg born aboard The Murray prior to her arrival at Port Adelaide.
Charlotte Downie Begg married Charles John Young on 27 December 1900. He was founder of the firm of C. J. Young shoe retailers.