The Red Ensign Group is a collaboration of United Kingdom shipping registries that include British Overseas Territories and Crown dependencies. It takes its name from the Red Ensign ("Red Duster") flag flown by British civil merchant ships. The group’s stated purpose is to combine resources in order to maintain a reputation for safety and quality across the British fleet. As of 2016 the Red Ensign Group ranked seventh in the world as measured by gross registered tons (GRT). Sir Alan Massey of the UK Maritime and Coastguard Agency commented ".. keeping [ships] inside the REG family means that you still have some influence over their quality and performance... We can take administrative measures against members of [it] if we want to so as to ensure that safety is brought up to the necessary standards..." The vessels also receive British Consular assistance and protection.
The Red Ensign Group has two categories:
A ship registered in any country within the Red Ensign group is entitled to fly the Red Ensign, or it can choose to fly the Red Ensign defaced with its home port national colors. As an example in 2011 the home port and registry of RMS Queen Mary 2 was changed from Southampton, Great Britain to Hamilton, Bermuda, a UK overseas territory. Despite the registry change she continues to fly the undefaced Red Ensign rather than the Bermuda Red Ensign.
Official site: http://www.redensigngroup.org/ The Red Ensign Group