At the tender age of just 15 Craig obliterated a high class field which featured training partner and former world record holder Jonathan Fox, who finished fourth, as he cruised to victory in 4:42.81.
He had already stunned the Aquatics Centre crowd with an eight-second personal best in his heat swim – taking Fox’s leading mark in the process.
And after taking the win he admitted his London experience had been more than he could possibly have hoped for.
He said: “It just goes to show surprising things can happen when you relax. I thought this is the last 400m of the season so why not go for it like I’ve never gone for anything before.
“I turned round and saw world record again and thought, 'this is a surprise'. I'm quite shocked by this – I might need a bit of therapy.
“I knew if I did everything I could, I would be happy whatever happened in the final but I’ve got a gold.”
In the final of the women’s 200m medley Britain had three swimmers in the mix for the medals, with Stephanie Millward and Louise Watkin claiming silver and bronze respectively behind defending champion Natalie Du Toit.
The South African claimed her 13th Paralympic gold medal ahead of an intensely British battle for the podium – with Claire Cashmore the unlucky odd one out in fourth.
Millward said: “That’s another two seconds off my personal best from before the Games which is fantastic.
“I really enjoyed that race. I enjoyed keeping up with Natalie really closely. It was our last race together and she gave me a huge hug at the end which was nice.”
Heather Frederiksen won her third medal of London 2012 with silver in a dramatic 100m freestyle – claiming ParalympicsGB’s 103rd medal of the Games to meet their target.
While USA's Jessica Long stormed ahead to set a world record 1:05.63, the Brit won the enthralling battle for silver as she held of Australia's Maddison Elliott and American Mallory Weggemann to take the touch in 1:08.07.
She said: “I'm so, so pleased with what I've done here.
"I knew it wasn't going to be easy coming in to this competition with the lack of training I've had through illness. But I've given it a good go and I'm really pleased with it.”
Finally Susie Rodgers completed a hat-trick of bronzes on her Paralympic debut with a gutsy performance in the 400m freestyle.
The 29-year-old, who has also lifted bronze in the 100m freestyle and 4x100m free relay, beat her European record for the second time in two races as she came home in 5:18.93.
The Brit insisted she was over the moon to have landed another medal in her fifth and final individual event of the Games.
“That was brilliant. It was a fantastic race,” said Rodgers.
“At the start of the meet I was very nervous, stressed and tense so I’ve tried to relax and enjoy it more. I really wanted a medal and that time is brilliant.”