John Richard Deacon was born on 19 August 1951 at St. Francis Private Hospital, London Road, Leicester to Arthur Henry and Lilian Mollie Deacon (née Perkins). His father worked at the Norwich Union insurance company and in 1960 the family moved to the dormitory town of Oadby. Deacon was known to friends and his bandmates as ‘Deacs’ or ‘Deacy’ and attended Linden Junior School in Leicester, Gartree High School and Beauchamp Grammar School in Oadby. He became interested in electronics, reading magazines on the subject and building small devices, including the modification of a reel-to-reel tape deck to record music directly from the radio. He studied well and achieved 8 GCE O level and 3 A level passes, all at grade A. He particularly enjoyed soul music.

Deacon joined his first band, The Opposition, in 1965 at the age of 14. The band played covers of chart hits; Deacon played rhythm guitar using an instrument he had bought with money borrowed from the group’s founder, Richard Young. He switched to bass the following year after the original bassist was fired for not improving his playing as much as the other members. As well as a dedicated musician, Deacon also was the band’s archivist, taking clippings from newspapers of even the advertisements featuring The Opposition. After being in the band for four years, not long after the group cut an acetate of three songs, Deacon played his final concert with the band (then called The Art) in August 1969. He left as he had been accepted to study at Chelsea College in London (now part of King’s College London), where he obtained a First Class Honours degree in Electronics in 1971. Having become a fan of Deep Purple, he saw the group perform the Concerto for Group and Orchestra with the Royal Philharmonic Orchestra at the Royal Albert Hall that September.

Although he left his bass and amplifier at home in Oadby, after less than a year of studying in London, Deacon decided he wanted to join a band. In 1970, Freddie Mercury, Brian May, and Roger Taylor had formed Queen; Deacon saw them in October that year but was not immediately impressed. Later in the year, he briefly formed a band called Deacon that made one live appearance at Chelsea College.

In early 1971, Deacon was introduced to Taylor and May by a friend at a disco who told him that they were in a band that had just lost its bassist. A couple of days later he auditioned in a lecture room at Imperial College London and became the last member of Queen to join. Deacon was selected for his musical talent, his quiet demeanour and his electrical skills. A persistent legend claims Deacon was the seventh bassist auditioned, but more recent sources show Queen’s bassists were, in order: Mike Grose, Barry Mitchell, Doug Bogie and Deacon. Deacon played his first show with Queen at the College of Estate Management in Kensington in June.

Deacon’s first bass, used in The Opposition, was an Eko, later switching to a Rickenbacker 4001. For most of Queen’s career, he used a Fender Precision Bass, which underwent a number of cosmetic changes. Towards the end of the group’s career, he used a custom bass designed by Roger Giffin. He also used an Ernie Ball MusicMan Stingray live on occasion. As a trained electronics engineer, he was able to build equipment for the band. His most famous creation is the “Deacy Amp”, built in 1972 from pieces of electronic equipment found in a skip, and used by himself and May throughout Queen’s recording career. Many of the so-called “guitar orchestras” on Queen albums use this amplifier.

In 1973, Rolling Stone wrote that the combination of Taylor and Deacon “is explosive, a colossal sonic volcano whose eruption makes the earth tremble.” Deacon played guitar in addition to bass, taking over rhythm parts on many albums, as well as several acoustic performances. Some of the guitar work on Hot Space (the clean Fender Telecaster single-coil sound) is Deacon’s. He would occasionally play synthesizers on his own compositions and often composed at the piano, playing a Wurlitzer electric piano on “You’re My Best Friend”. He can also be seen playing the grand piano in the music video to “Spread Your Wings”, although on the actual recording the piano was played by Mercury. Unlike the other three members of Queen, Deacon did not sing on the group’s records, though he did occasionally sing backing vocals during live performances.

Deacon has often been described as the “quiet” member of the band. Although the rest of the band felt he was the right bassist for them, he barely spoke in rehearsals and avoided arguments. He lives in Putney in Southwest London with his wife Veronica Tetzlaff, whom he married on 18 January 1975, and is the father of six children. One of the reasons for Queen splitting from Trident, their original management company, is that it refused to lend Deacon money to put a deposit on a house.

Deacon played a larger role on the band’s 1982 album Hot Space. He played rhythm guitar on the opening “Staying Power” because of his soul and Motown-influenced style, and insisted on playing guitar on his own composition “Back Chat” and not allowing May to play any guitar solos because the style did not fit what Deacon wanted. This led to an acrimonious argument between the two. By the mid-1980s Deacon had started to play with other bands as well. He performed on the single “Picking Up Sound” by Man Friday & Jive Junior, a supergroup also featuring Thin Lizzy’s Scott Gorham, Bad Company’s Simon Kirke and Mick Ralphs, and The Pretenders’ Martin Chambers. and played with The Immortals, which released the track “No Turning Back” as part of the soundtrack to the film Biggles: Adventures in Time. Deacon played bass on Mercury’s single with Montserrat Caballe “How Can I Go On” and also worked with Elton John and Hot Chocolate’s Errol Brown.

Deacon was upset the most by Mercury’s death in November 1991, which resulted in a reduction in his musical activity. He said, “As far as we are concerned, this is it. There is no point carrying on. It is impossible to replace Freddie.” After playing live with Queen three more times – at The Freddie Mercury Tribute Concert for AIDS Awareness on 20 April 1992, in a charity concert with Roger Taylor at Cowdray House in Midhurst on 18 October 1993, and at the opening of the Bejart Ballet in Paris on 17 January 1997, performing only “The Show Must Go On” with Elton John on lead vocals – he decided to retire from music, re-appearing only briefly by joining his former bandmates in October 1997 for the recording of the final Queen song “No-One but You (Only the Good Die Young)”, included on the Queen Rocks album released a month later.

Deacon has stayed out of the public eye since retiring. He chose not to be present at Queen’s induction into the Rock and Roll Hall of Fame in 2001. He also did not join the collaboration with singer Paul Rodgers (as Queen + Paul Rodgers), where he was replaced on bass by Danny Miranda. On the Queen + Paul Rodgers collaboration album The Cosmos Rocks which featured new material from the trio, he was thanked in the notes on the CD. Brian May has since said that Deacon is still involved on the business side of Queen but chooses to stay out of the limelight. May also confirmed that Deacon approved of the making of the band’s biopic Bohemian Rhapsody, where he was played by Joseph Mazzello.

In 2013, a newly-discovered species of the genus Heteragrion (Odonata : Zygoptera) from Brazil was named Heteragrion johndeaconi after Deacon, in honour of his musical and songwriting skills – one of four Heteragrion flatwing damselflies named after the bandmates, paying tribute to the 40th anniversary of Queen’s founding.

In a 2014 interview with Rolling Stone magazine regarding the forthcoming Queen + Adam Lambert North American tour with Adam Lambert, May and Taylor admitted that they no longer have much contact with Deacon except regarding finances, with Taylor stating that “[Deacon]’s completely retired from any kind of social contact”, and describing him as “a little fragile”. May added, however, “he still keeps an eye on the finances, though. John Deacon is still John Deacon. We don’t undertake anything financial without talking to him.” Session bassist Neil Fairclough covered the tour.