These changes resulted in a continuous block of British-controlled territories from the Zambezi northwards in which, following the principles first set out in 1923 by the Duke of Devonshire, who was then Colonial Secretary, the interests of Africans would be treated as paramount.
In time, major funding was also contributed by the countries involved, while in Trinidad the British government and neighbouring British-controlled territories also assisted.
It was the sort of route the British had long been anxious to create, an all-red one, passing through either British-owned, British-run or British-controlled territory.
And not at all from the British-controlled territory beyond, Judson added silently.
As Saudi expansion slowed in the 1920s, some among the Ikhwan pushed for continued expansion, particularly to the British-controlled territories such as Transjordan to the north - where the Ikhwan raided in 1922 and 1924.
The estates of outspoken Loyalists were seized; they fled to British-controlled territory, especially New York City.
Ehelepola fled to British-controlled territory, where he persuaded the British that Sri Vikrama Rajasinha's tyranny deserved a military intervention.
The European colonialists used the Congo-Nile divide as a boundary between British-controlled territories to the east and territories controlled by the French and Belgians to the west.
Similarly in India, the French armies and those of the most powerful Indian rulers were defeated after a prolonged struggle, allowing the steady expansion of British-controlled territory.