After a low-key first half which failed to impress the crowd of 50,157 at St James' Park, Marchant's solo try after 53 minutes roused them as England scored four second-half tries from 9-0 up at the break.
England has never lost to Italy in 25 previous tests, and the Italians, who were without rested skipper Sergio Parisse, never looked like breaking their duck as they concluded their World Cup buildup in untidy fashion.
For the English it was job done, as they followed up victories over Wales and Ireland with a competent display against the limited Azzurri to offset their narrow defeat in Cardiff. Jones fielded 20 of his 31-man World Cup squad that will fly out to Japan on Sunday, and he will be anxious to check on the fitness of lock Joe Launchbury after he limped out of the action six minutes before halftime.
Bath winger Ruaridh McConnochie got an early touch to ease his nerves on his long-awaited debut, but most of the action took place on the other wing, where the experienced Jonny May caught the eye with a typically strong performance.
May spoiled Italy's best try opportunity early on, stripping the ball from center Tommaso Benvenuti after Italy went through 22 phases. Scrumhalf Ben Youngs scored the first try after strong surges by Ellis Genge and Kyle Sinckler, then Youngs passed to Marchant, who blew past four defenders to score between the posts and put the result beyond doubt.
Italy's interest fell away, and England finished with tries to Genge and Anthony Watson, and Owen Farrell landed his seventh goalkick from eight attempts. England begins the World Cup against Tonga on Sept. 22 in Sapporo, and Italy plays on the same day against Namibia in Higashiosaka.
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