GOLD COAST, Australia - Flags flew at half mast as hundreds of mourners gathered here to bid farewell to Formula 1 great Sir Jack Brabham at a state funeral during which he was revered as "a national treasure".He was laid to rest in a coffin adorned with a steering wheel and crash helmet and draped in a chequered racing flag - the one that, fittingly, marks the end of a race.Brabham won three Drivers' titles and is still the only person to win the championship in a car he built himself. He died in May, aged 88. His funeral had to be delayed because of the racing commitments of his grandsons Sam and Matthew.A third son, Geoffrey, explained: "Dad would have got out of his coffin and kicked their arse if they'd missed a couple of matches for him."INFLUENTIAL FIGURES The Australian was one of the motorsport's most influential figures thanks to technological innovations brought about by the team he created. He was the first driver to be knighted for services to motorsport.The Australian F1 GP winner's trophy was this week renamed in his honour.Geoffrey Brabham added: "He was a legend and a giant not only in motor racing but in all Australian sport."Australian GP chief executive Andrew Westacott called him "a national treasure" who "just took on the world and won" and a message from Australian prime minister Tony Abbott hailed his "have-a-go spirit".