The phrase East of Suez is used in British military and political discussions in reference to imperial interests beyond the European theatre (sometimes including, sometime excluding the Middle East).
The origin of the phrase is a quotation from the poem Mandalay, written by Rudyard Kipling, which became a popular song when a tune was added by Oley Speaks.
Previously, the empire's military infrastructure drew on sea lanes of communication through the Mediterranean Sea via the Suez Canal, alternatively round the Cape of Good Hope to India, and on to East Asia (Brunei, Burma, British Malaya, Hong Kong, North Borneo, Sarawak) and Australia. With the end of empire, which began with Indian independence (1947), there was a gradual draw down of the military presence "east of Suez".
In 1968, Prime Minister Harold Wilson and his Defence Secretary, Denis Healey, announced that British troops would be withdrawn in 1971 from major military bases in South East Asia, primarily in Malaysia and Singapore as well as Aden and Maldives (both of which are sited in the Indian Ocean), which is when the phrase in that context entered the vernacular.
In June 1970, Edward Heath's government came to power and retained a small political and military commitment to South East Asia through the Five Power Defence Arrangements.
Prior to the 1997 handover of Hong Kong to China, Britain based several units in Hong Kong.
As of 2010, Britain maintains the School of Jungle Warfare in Brunei and a battalion of the Royal Gurkha Rifles, in addition to some aircraft of the Army Air Corps, as part of the British Military Garrison Brunei. There is also a small British military presence remaining on Diego Garcia in the British Indian Ocean Territory, as well as a refuelling station (manned by Royal Navy personnel) in the former HMNB Singapore in Singapore.[1]