Scorecard :
England claimed their huge victory before lunch on the fourth morning when Tim Bresnan had Ben Hilfenhaus caught behind for a duck and incapacitated Ryan Harris was unable to bat because of an ankle injury.
There was only going to be one result after Australia were routed for a ground record low of 98 on Sunday's opening day after Andrew Strauss won the toss and put the Australians into bat on a bowler-friendly wicket.
The English responded with a towering 513 to hold an impregnable 415-run innings lead which Australia found totally beyond them.
It was the first time England had won the Ashes Down Under since Mike Gatting's team claimed the series 2-1 in 1986-1987.
Australia can still level the series if they can fight back and win next week's fifth Sydney Test, but the Ashes are gone.
England last won at the MCG in 1998 with Dean Headley taking 6-60 in the second innings as the tourists won by just 12 nail-biting runs and it was only Australia's second defeat in their last 12 MCG Tests.
Overall it was England's 20th win in 54 Ashes Tests at the MCG.
Match scores: Australia 98 and 258 for 9; England 513.
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