In 1946 the AELTC offered employment to wartime servicemen returning to civilian life during their demobilisation leave. Initially, this scheme extended only to the Royal Navy, followed by the British Army in 1947 and the Royal Air Force in 1949. In 1965 London Fire Brigade members joined the ranks of stewards. The service stewards, wearing uniform, are present in Centre Court and No.'s 1, 2, 3, 12 and 18 courts. In 2015, 595 Service and London Fire Brigade stewards attended. Only enlisted members of the Armed Forces may apply for the role, which must be taken as leave, and half of each year's recruits must have stewarded at Wimbledon before. The AELTC pays a subsistence allowance to servicemen and women working as stewards to defray their accommodation costs for the period of the Championships. The Service Stewards are not to be confused with the 185 Honorary Stewards. The majority of centre and show court tickets sold to the general public have since 1924 been made available by a public ballot that the All England Lawn Tennis and Croquet Club holds at the start of the year. The ballot has always been substantially oversubscribed. Successful applicants are selected at random by a computer. The most recent figures from 2011 suggested there were four applicants to every ballot ticket. Applications must be posted to arrive at the AELTC by the last day of December in the year prior to the tournament. Seats and days are allocated randomly and ballot tickets are not transferable. The All England Club, through its subsidiary The All England Lawn Tennis Ground plc, issues debentures to tennis fans every five years to raise funds for capital expenditure. Fans who invest thus in the club receive a pair of tickets for every day of the Wimbledon Championships for the five years the investment lasts. Only debenture holders are permitted to sell on their tickets to third parties and demand for debentures has increased in recent years, to such an extent that they are even traded on the London Stock Exchange. Wimbledon and the French Open are the only Grand Slam tournaments where fans without tickets for play can queue up and still get seats on the three show courts on the day of the match. Sequentially numbered queue cards were introduced in 2003. From 2008, there is a single queue, allotted about 500 seats for each court. When they join the queue, fans are handed queue cards. Anyone who then wishes to leave the queue temporarily, even if in possession of a queue card, must agree their position with the others nearby in the queue and/or a steward.