Volunteer Reserves (United Kingdom)

The Volunteer Reserves are the British Armed Forces voluntary and part-time military reserve force. Unlike the Regular Reserve, the Volunteer Reserves do not consist of ex-Regular personnel who remain liable to be re-called for military service. Instead, the Volunteer Reserves consists of civilian volunteers who routinely undergo training and military operations alongside the Regular military. The Volunteer Reserves serve under a fixed-term reserve contract and provide "highly trained" military personnel integrated with their Regular counterparts, on operations both at home and overseas. For example, almost every major military operation has seen the deployment of Army Reservists alongside the Regular British Army. Volunteer Reserves are allowed to use the post-nominal letters VR after 10 years of service.

The Volunteer Reserves also includes the armed forces University Service Units (incl. below). These training units are not liable for military service, rather, they provide engagement and military training for undergraduate students at UK universities.

Volunteer Reserve units
The Volunteer Reserves primarily consist of four elements, each being an integrated part of their parent service and liable for military operations. University Service Units are listed with their parent organization:
 * Army Reserve – (incl. Officers' Training Corps)
 * Maritime Reserve
 * Royal Naval Reserve – (incl. University Royal Naval Units)
 * Royal Marines Reserve
 * RAF Reserve
 * Royal Auxiliary Air Force
 * Royal Air Force Volunteer Reserve – (incl. University Air Squadron)

Future Reserves 2020
As part of the "Future Reserves 2020" review conducted in 2012, the Volunteer Reserves (excluding University Service Units) will be fully integrated with the Regular Armed Forces and better prepared for overseas deployments and operations.

Call-out
Under the Reserve Forces Act 1996, fully mobilising or "calling-out" the Volunteer Reserves for active service can only be made by a royal proclamation on the advice of the Secretary of State for Defence under specific circumstances: "(a) if it appears to [the monarch] that national danger is imminent or that a great emergency has arisen; or (b) in the event of an actual or apprehended attack on the United Kingdom." However, in the case of lesser events, the Secretary of State can call-out those who have accepted a "special agreement" making them liable for up to 12 months of active service if required.