Invariably introduced on stage by his boss as “Phantom Dan”, the keyboardist Danny Federici played with Bruce Springsteen for 40 years and helped to define his trademark sound as a key member of his E Street Band.

Danny Federici was born in 1950 in Flemington, New Jersey. His first instrument was the accordion, on which he was a child prodigy, appearing at clubs and on the radio at the age of 7. Classically trained, he added the piano to his instrumental repertoire and then the organ.

He met Springsteen on the Asbury Park rock scene in the mid-1960s when he earned the nickname “Phantom”, allegedly as a result of a minor youthful misdemeanour in which various others were arrested but Federici managed to escape.

In the late 1960s he formed the band Child with the future E Street Band drummer Vini Lopez. In search of a singer, they invited Springsteen to join them — “a skinny guy with long hair and a ratty T-shirt”.

When it was discovered that there was a rival band also called Child, they became Steel Mill but by early 1971 the group had broken up. Springsteen had already emerged as the leader, and when he briefly formed Dr Zoom And the Sonic Boom and then the Bruce Springsteen Band, Federici joined both.

As Springsteen rocketed to fame, Federici’s keyboards were always there to back him as required, both on record and on stage. Notable contributions to the Springsteen canon included the accordion on 4th of July, Asbury Park (Sandy) on the 1973 album The Wild, the Innocent and the E Street Shuffle and the organ solo on Hungry Heart, Springsteen’s first American Top Ten hit in 1980.

Even when Springsteen dispensed with the full E Street Band on such acoustic albums as The Ghost of Tom Joad (1995) and Devils and Dust (2005), he retained the services of Federici, whose playing was also heard to particularly potent effect on Springsteen’s 2002 album The Rising, inspired by the events of 9/11.

They came together again in 2004 for the Vote for Change tour, campaigning against the re-election of George Bush. In November 2007 he took a leave of absence from Springsteen’s touring band to undergo treatment for melanoma but made an emotional return a month before his death for one concert only in Indianapolis on March 20, 2008.

On the news of his passing , Springsteen immediately cancelled his next two concerts as a mark of respect. “Danny and I worked together for 40 years,” he said in a statement on his website. “He was the most wonderfully fluid keyboard player and a pure natural musician. I loved him very much.”

Away from his work with Springsteen, Federici recorded two jazz-orientated solo albums, Flemington (1997) and Out of a Dream (2005). He also played on albums by a vast number of other artists including Steve Van Zandt, Joan Armatrading, Graham Parker, Gary “US” Bonds and Garland Jeffreys.

Danny Federici, musician, was born on January 23, 1950. He died of cancer on April 17, aged 58