England scored two late tries through captain James Chisholm and replacement wing Will Haywood to secure a hard-fought victory in front of more than 1,000 spectators at Harrow School. Tom Morton added nine points with the boot and Aaron Morris kicked four more.
England started brightly and went ahead with ten minutes played through Sale Sharks fly-half Morton, and he was on hand to add two more penalties to extend the hosts' lead to 9-0 shortly afterwards.
Australia struggled to get a foothold in the game and their troubles increased when Andrew Deegan was sent to the sinbin for talking back to referee Ben Whitehouse.
But the tourists rallied and after England centre Nick Tompkins was shown a yellow card – also for talking back to the official – Deegan returned to the pitch to get his side on the board and make it 9-3.
After a slow start to the second period, England finally made the breakthrough with just over ten minutes remaining. A break from Tompkins created space for Howard Packman, who found Chisholm to force his way over from 15 metres.
In the last phase of play England sent passes through the hands, eventually finding Haywood who scored from close range.
England Under 18s starting XV against Australia
15 Aaron Morris (Bedford Blues)
14 Josh Skelcey (Northampton Saints)
13 Nick Tompkins (Saracens)
12 Max Clark (Bath Rugby)
11 Howard Packman (Northampton Saints)
10 Tom Morton (Sale Sharks)
9 Stuart Townsend (Exeter Chiefs)
1 Lewis Boyce (Leeds Carnegie)
2 Jack Walker (Leeds Carnegie)
3 Paul Hill (Leeds Carnegie)
4 Kieran Treadwell (Harlequins)
5 Charlie Ewels (Bath Rugby)
6 Joe Batley (Gloucester Rugby)
7 Will Owen (Leicester Tigers)
8 James Chisholm (Harlequins) (c)
16 Ollie Adams (London Irish)
17 Luke Chapman (Exeter Chiefs)
18 Ciaran Parker (Sale Sharks)
19 Will Witty (Newcastle Falcons)
20 Andrew Boyce (Worcester Warriors)
21 Rory Jennings (Bath Rugby)
22 Theo Brophy-Clews (London Irish)
23 Will Haywood (Gloucester Rugby)