* Diagnosed with lung cancer in October
* Key figure in Cricket World Series revolution
MELBOURNE, Dec 29 (Reuters) - Former England captain and respected commentator Tony Greig, one of the architects of cricket's World Series revolution in the 1970s, has died at the age of 66 after suffering a heart attack at his Sydney home on Saturday.
Greig, who was diagnosed with lung cancer in October, was taken to a Sydney hospital but died at about 1:45 pm (0245 GMT).
"The staff of the emergency department worked on Mr Greig to no avail," a spokesman at St Vincent's hospital told local media.
A larger-than-life figure standing 6ft 6in (1.98m), South Africa-born Greig played 58 tests for England from 1972-77 as a successful all-rounder, scoring 3,599 runs for a batting average of 40.43 and claiming 141 wickets.
His biggest impact on the game, however, came after he joined forces with late Australian businessman Kerry Packer to set up the breakaway World Series Cricket (WSC) competition.
Media magnate Packer's concept, aimed at securing cricket broadcast rights for his Channel Nine in Australia, shook up the game's world order by pioneering limited overs matches played at night and turning cricketers into full-time professionals.
Greig's signature lent credibility to WSC and he played a key role in recruiting disaffected players to the controversial competition.
"He influenced all those guys from overseas, certainly, and the West Indies to join World Series Cricket and it was great for cricket what he had done," former Australia batsman Doug Walters, who played in the WSC competition, told Sky News.
"Greig was one of the great competitors of cricket ... He was someone that really took the fight to Australia, but he took the fight to everybody.
"Win, lose or draw he was the first guy in our dressing room with a couple of beers in his hands."
Greig's recruitment to WSC's cause put him at loggerheads with cricket's conservative establishment and he was stripped of the England captaincy in 1977. His international career ended shortly after.
A long-time resident Down Under, Greig later became a cricket commentator with Channel Nine, having been promised a "job for life" by Packer.
A combative and occasionally abrasive character, Greig's booming voice and signature white hat featured on Australian television screens for over three decades, but his battle with cancer prevented him from taking his position behind the microphone for the current 2011/12 season.
"It's a great loss to world cricket. To me personally I'm shattered," said former Australia captain Bill Lawry, who spent decades alongside Greig in Nine's commentary box.
"World cricket's lost one of its greatest ambassadors."
Tributes flowed for Greig, who went from being a villain to a highly-respected cricket pundit in his adopted country.
"RIP Tony Greig!! You have left a great footprint on the world of cricket. My condolences to the Greig family," retired West Indies batting great Brian Lara said in a post on his Twitter account.
"Not only was he a wonderful player and a very successful player for England, I think he was a wonderful guy," Australia captain Michael Clarke told Australian television.
(Reporting by Ian Ransom; Editing by Peter Rutherford; firstname.lastname@example.org)