Two Owen Farrell penalties settled any early England nerves but two tries on the stroke of half-time turned the game on its head.
First Venditti, who has been a tower of strength for Aironi in the RaboDirect PRO12 this season, barged over after a Kris Burton grubber kick caused panic in the England defence.
And a minute later Italy hit the front as Benvenuti intercepted a Ben Foden pass to streak clear and touch down under the posts.
After the break Italy continued to threaten but Charlie Hodgson charged down an attempted clearing kick from Aironi's Andrea Masi before touching down.
And the metronomic right foot of Farrell kept England ticking over as they hit the front with two more of his penalties.
And the decision to take off Burton came back to bite the Azzurri as without the Treviso fly-half replacement Tobias Botes missed with two penalties late on let England off the hook.
Guinness PRO12 Aironi News
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