The cathedral was built by the UMCA Universities Mission to Central Africa which answered a call from David Livingstone 'to help Christianize the people of The Dark Continent and do their best to oppose slavery. This group eventually settled on the Lake in 1884 because the climate was less devastatingly malarial and denguey: you can't convert the heathen if you are dead. The investment of British money, British missionaries and British architectural standards was key to establishing British hegemony over these islands despite them being much closer to the Portuguese/Mozambique shore.
The Portuguese colonial government sat down with their British counter-parts in the 1950s to thrash out the common ground and iron out any difficulties between the two empires. They agreed to a series of drainage and flood control works around the Shiré River, the plug-'ole of the Lake, which drains from Lake Malawi and eventually joins the Zambesi deep in Mozambique. In exchange for owning a third of the cost of these public works, the Portuguese got access to the fishing up to the median line of the lake . . . excluding the Likoma archipelago. These signed-off economic and political agreements between colonial powers established the default position on the boundaries for the independent states of Malawi and Mozambique. Protestant Missions converted 60% of the people of Malawi.