Gloucester were represented by back row Joe Batley and wing Will Hayward who was a late call up to the squad. Both are students at Hartpury as well as membes of the Gloucester U18s set up.
But scores from captain James Chisholm and replacement wing Will Hayward secured the win, with Tom Morton's boot adding nine points and Aaron Morris' four.
England started brightly and went ahead with ten minutes played through Sale Sharks No. 10 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 were exacerbated when playmaker and No. 10 Andrew Deegan was sent to the sinbin for talking back to Welsh 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 left to play. A break from Tompkins freed up space for Howard Packman, who in turn found Chisholm, the skipper powering over from 15 metres out.
In the last phase of play England sent passes through the hands in Harlem Globetrotter-like style, the ball eventually falling to Hayward - a late inclusion to the squad - who made no mistake from close range.
Speaking after the win, Fletcher said:
"I'm delighted for the guys - I thought that the scoreline reflected the game, it just took us a little while to get going but the fact that we didn't give in, and we kept on pushing, is a real testament to their character and I'm really pleased that they were able to get the win."
BMW Man of the Match Nick Tompkins added:
"We're delighted to get the win - it was a really tough match against tough opposition. I felt that we maybe tried too much in the first half but as the game carried on we opened them up a little bit and that was pleasing.
"We're a close group and this win showed that I think, it wasn't going all our way but we stuck at it and, as I say, we're delighted."
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)
Replacements (all used)
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 Hayward (Gloucester Rugby)
Content courtesy of RFU