The Retained Firefighters Union or RFU is the British trade union dedicated to representing retained firemen.
A "retained fireman" or firefighter is simply a part-time fireman. The British fire service relies a great deal on individuals that already have a full time job, but agree to turn out when an emergency call is made. At any one time, over half the firefighting appliances within the United Kingdom are manned by retained as opposed to full time firemen.
The UK already has a trade union, the Fire Brigades Union or FBU, that already represents firefighters in general, but the RFU was formed in 1976 due to dissatisfaction with the FBU and a belief that they ignored the interests of the retained part of the workforce. There is therefore a great deal of rivalry and mudslinging between the two unions; the FBU bitterly resents a competing union intruding on its patch and the RFU is constantly sniping at the FBU for failing to properly represent the part-timers.