Town legend Paul Mariner has died aged 68, his family has announced.
In a statement, they said the former striker "passed away peacefully on 9th July surrounded by his family, after a brief battle with brain cancer”.
Bolton-born Mariner joined the Blues from Plymouth in 1976 for a fee of £220,000 with John Peddelty and Terry Austin moving in the opposite direction.
The centre-forward went on to become a key man in Sir Bobby’s Robson’s teams which won the FA Cup in 1978 and the UEFA Cup in 1981.
An England regular throughout his time with the Blues, Mariner won 35 caps and scored 13 times, including the goal which saw England qualify for the 1982 World Cup via a 1-0 victory over Hungary at Wembley.
He left Town for Arsenal for a fee of February 1984 for £150,000 having made 339 appearances and scored 135 goals. In 2011 he was inducted into the Town Hall of Fame.
Prior to his time at Plymouth, Mariner had started his career at Chorley in non-league. Following his spell with Arsenal, he spent time at Portsmouth, Wollongong City, Albany Capitals and San Francisco Bay.
After hanging up his boots, he worked as a pundit for BBC Radio Lancashire, then spent most of the next few years coaching in the US where he worked in Arizona and then at Harvard before a five-year spell as assistant manager at the New England Revolution.
He returned to the UK to manage Plymouth in 2009/10 and was given a rapturous welcome by Town fans on his return to Portman Road.
A stint in charge of Toronto FC in Canada followed in 2012/13 followed before he spent time working as a pundit in the US while based in Boston.
In November it emerged that Mariner had undergone surgery to remove a brain tumour.
Town CEO Mark Ashton led the tributes to a player many believe was the best striker ever to represent the club.
"It’s incredibly sad news and the thoughts of everyone at the club are with Paul's family and friends at this very difficult time,” Ashton told the club site.
Town are set to wear black armbands at this afternoon’s friendly at Dartford as a mark of respect.