Having started with two penalties, Cipriani weighed in with one of England's five tries and also chipped over four conversions before making way for Toby Flood four minutes from the end.
England led 20-10 at the break, but were made to work very hard in wet conditions by a typically committed Islanders outfit. First half tries from the Wasps duo of Paul Sackey and Cipriani laid the foundation for that 10 point interval lead before the gap was extended to 21 points after 68 minutes.
Sackey got a second try after the break and there was joy for London Irish lock Nick Kennedy as he marked his debut with a try. Bath hooker Lee Mears was the fifth try scorer.
"We need to improve a lot in areas of the game, but we got there in the end in what was a pretty tough game in wet conditions, '' Johnson admitted in his post match interview on Sky Sports.
Johnson also had some special words of praise for London Irish full back Delon Armitage following his impressive debut.
"I thought he was outstanding. I just said to him 'I don't think I have ever seen a better debut'," added Johnson
"He looked great. He has trained like that. But some players train like that and don't play like that."