There was never an official flag that represented the British Empire save the Union Flag of the United Kingdom of Great Britain and (Northern) Ireland.
However, here are some flags and badges that have been found on the internet with an empire theme:
Top: This flag shows the British white ensign with the official coat of arms of Australia, Canada and News Zealand in the quarters and the United Kingdom's in the centre.
Bottom: This flag shows the British white ensign with the official coat of arms of Australia, Canada and News Zealand in the quarters and the Queen's Personal Emblem in the centre.
These flags are a more modern creation of the flag shown on the far right which included the Union of South Africa and India.
This flag shows the Union flag defaced with the Royal Coat of Arms in the centre, surrounded by the royal flags of England, Scotland, Ireland and the flag of Wales with Britannia above, centre.
This flag shows the British white ensign with the reduced coat of arms of South Africa, New South Wales/Australia and Canada with the stars of New Zealand on the cross of St. George and the Star of India, centre.
This flag has been reportedly used.
This flag shows the Union flag defaced with Britannia in the centre surrounded by a garland of flowers and plants representing countries of the British Empire
A 'United Empire' lapel pin
Animals shown represent Australia (Kangaroo), Beaver (Canada), Elephant (India or Africa?) and a Moa (extinct bird from New Zealand)
Any help with this badge or if you have another badge representing the British Empire - would be gratefully appreciated.
The dog on the Union flag was Queen Victoria's dog Dimboola and above was the Imperial Crown.
Curtesy of John Johnston
Designed in November 2011 by James Alcock, this is the flag we feel would represent the 'Empire Flag' above in today's era.