But it wasn't all plain sailing for England, as Ireland kept the scoreboard ticking through the boot of Dungannon's Paddy Jackson and his replacement James McKinney, both taking advantage of the high penalty count against England.
England got off to a dream start though, after forcing a scrum deep in Ireland's territory with two minutes played. Bath scrum half Chris Cook got the ball out quickly and smooth passing across the field cumulated in Worcester wing Andy Short flying over in the corner, with Ford converting.
Ford extended England's lead to 13-0, coolly dispatching two penalties after Irish infringements at the breakdown. Ireland missed two penalties of their own when Jackson kicked just wide both times. Jackson made no mistake with his third attempt though, slotting through with half an hour played to make the score 13-3.
England thought they had scored after a Ford grubber was taken by Short over the try line, but South African referee Jaco Peyper, deemed it not to have been touched down. Ireland then broke straight away through Blackrock College wing Andrew Conway who's attempted kick up field deflected kindly off England skipper Alex Gray's back and Conway collected before running through to touch down.
Heavy pressure from the restart allowed England to push hard on Ireland's try-line, and good work from Vunipola freed up space for Thomas to touch down. Ford missed the conversion, and Ireland scored a late penalty to take the score to 18-13 at the break.
England brought on Premiership winner Owen Farrell for Ryan Mills, but it was Ireland who drew first blood in the second half when Jackson scored a penalty to bring the Irish to within two points.
Just as things started to look very tense, Vunipola produced a solo try for England belying his position of tight-head. A lovely sidestep and brute strength freed the former Bristol prop up to dive over, giving England a 23-16 lead after Ford's conversion attempt hit the post.
Ireland's McKinney missed and then scored two penalties in quick succession to bring the Irish to within a point of England at 23-22.
McKinney then gave Ireland the lead for the first time in the match with 10 minutes remaining, converting another penalty. But England hit back with one of their own from Ford to give England the lead back at 26-25.
Ireland then had to contend with the sinbinning of back rower Shane Buckley and England made the most of the man advantage, as replacement wing Marland Yarde dived over in the corner to give England breathing space at 31-25, before Ford converted and England held out to win 33-25.
Points: Andy Short 1T, Henry Thomas 1T, Mako Vunipola 1T Marland Yarde 1T; George Ford 2C, 3P
England U20 starting XV v Ireland
1) Mako Vunipola (Saracens)
2) Mike Haywood (Northampton Saints)
3) Henry Thomas (Sale Sharks)
4) Joe Launchbury (London Wasps)
5) Charlie Matthews (Harlequins)
6) Matt Kvesic (Worcester Warriors)
7) Matt Everard (Leicester Tigers)
8) Alex Gray © (Newcastle Falcons)
15) Ben Ransom (Saracens)
14) Andy Short (Worcester Warriors)
13) Elliot Daly (London Wasps)
12) Ryan Mills (Gloucester Rugby)
11) Jonathan Joseph (London Irish)
10) George Ford (Leicester Tigers)
9) Chris Cook (Bath Rugby)
16) Rob Buchanan (Harlequins)
17) Ryan Bower (Leicester Tigers)
18) Sam Twomey (Harlequins)
19) Sam Jones (London Wasps) on for Matt Everard 55 mins
20) Dan Robson (Gloucester Rugby) on for Chris Cook 60 mins
21) Owen Farrell (Saracens) on for Ryan Mills 40 mins
22) Marland Yarde (London Irish) on for Jonathan Joseph 50 mins