The British Imperial lifeline is a term used to describe the route by which Imperial England was connected to her colonies in the far east, most notably India.
The lifeline ran as follows:
Southern England → Gibraltar → Malta → Alexandria in Egypt (for the Suez Canal) → India and Sri Lanka.
The Imperial Lifeline was vital for the Empire's power and was protected and maintained by the powerful Royal Navy. The Lifeline ceased to exist with the end of the British Empire.
The lifeline arguably got its start thanks to the efforts of the British East India Company, whose efforts along the lifeline brought immense wealth to the crown.