MacDonnell was called to the Irish bar in 1838, and to the English bar, at Lincoln's Inn, 25 January 1841. On 20 July 1843, he was appointed to the new post of Chief Justice of the Gambia. After four years there, amidst long breaks for his health travelling through the United States and Canada, he intended to hand in his resignation to Henry Grey, 3rd Earl Grey and resume practice at the English bar. But, on 1 October 1847, Grey persuaded him otherwise and appointed him Governor of the British settlements in Gambia, a post he held for a further four years.
While in Gambia, MacDonnell (a cousin of the explorers Captain Sir Richard Francis Burton and Admiral Richard Charles Mayne) spent much of his time indulging his passion for exploration, and organising punitive campaigns against unruly native tribes. His expeditions opened up the interior of Africa from the Gambia River to the Senegal River. The military expeditions which he accompanied against native tribes who had long oppressed the traders of the river were a success and extended the limits of British commerce in the region. On one visit to a native king an ambush was laid for him, and he narrowly avoided being assassinated. In return, the British government sent four hundred men to inflict a summary chastisement, with MacDonnell acting as Captain of one of the volunteer companies.[3]
Soon after his arrival in Australia, MacDonnell was involved in heated debate over the composition of the legislature; MacDonnell favoured a single chamber while the majority of colonists preferred a two-house system, which brought him the support of the conservatives, but united the liberals and radicals against him. Eventually a two-house system prevailed, although the Upper House had a property franchise. Difficulties between MacDonnell and his officials led to several changes of government. He extended railway and telegraph communications within the colony and opened up valuable copper mines on the Yorke Peninsula, while increasing the progress in agricultural and pastoral pursuits.
MacDonnell showed little concern for the Australian working class, holding that charity fostered sloth and pauperism. He was particularly impressed with the settlers from Germany, and he predicted that the colony had a great future for producing wine. In his seven-year term the acreage under wheat doubled in South Australia and he argued that farmers with capital would succeed as long as their methods did not rob the soil.
MacDonnell's passion for exploration greatly aided in opening up the interior of Australia, in particular the Murray River, and he developed many of the natural resources of the colony. He travelled widely in the colony and in 1859 led a small party to investigate country around the northern lakes and claypans, riding 1,800 miles (2,900 km) in three months. He maintained that Charles Sturt and Edward John Eyre were overrated as explorers as they seemed "generally to have a knack of getting into the most dismal places and finding barrenness from Dan to Beersheba". He instead urged the colonists to support the efforts of John McDouall Stuart to cross the continent.
MacDonnell was regarded in Australia as both 'powerful and hospitable'. He was an enthusiastic member of local rifle and archery clubs and keenly interested in the volunteer defence movement. He also identified himself with most of the literary, artistic and philanthropic organizations. He saw himself as a leader and innovator, and though genial, at times his bustling energy dismayed Adelaide society. As a patron of South Australian culture he encouraged students who could not travel abroad to continue their post-primary schooling, and with his customary dash personally examined candidates and donated prizes, but his plan collapsed after he left the colony. He left South Australia, 4 March 1862, for a holiday in Ireland before taking up his next post.
On 19 October 1865, MacDonnell was appointed as the sixth Governor of Hong Kong, a position in which he served until 1872. During his tenure, MacDonnell developed Victoria Peak, which would eventually become the premier residential quarters in Hong Kong, accessible only to rich European merchants. MacDonnell also ordered the construction of a hospital which catered to the needs of the local Chinese population. In addition, he legalised gambling in Hong Kong which led to social problems and was later made illegal once again. In 1871 he was gazetted K.C.M.G.
Finally, MacDonnell's administration was marred by a huge budget deficit, which resulted in the government asking the HSBC for a financial aid package. The administration was also damaged by the actions of the Canton Customs agency, who patrolled the waters off Hong Kong and boarded ships to search for smuggled goods. This was called by Hong Kong's British merchant community a blockade, and affected Hong Kong's economy for the next 20 years.
Marriage and retirement
The grave of Sir Richard Graves MacDonnell, Kensal Green Cemetery
In 1847, MacDonnell married Blanche Ann, daughter of Francis Skurray of Beckington, Somerset, who lived at Stanhope Place, Hyde Park and Percy Cross Lodge, Fulham, before retiring to 5 Brunswick Square, Brighton. Sir Richard and Lady MacDonnell lived near Hyde Park in London and after his retirement in 1872 they spent much time in Italy and France; Sir Richard died at Hyères, 5 February 1881.
Both are buried in Kensal Green Cemetery, on the southern side. They died without children.
Publications with his involvement
The Church of the Future, an address by the Rev. Thomas Binney in 1859
Christian Union, as discussed by the Bishop of Adelaide