The 18-year-old's dreams of joining sister and world champion sprinter Libby, who is also partially sighted, at the Games appeared to be over earlier this year when he failed to hit the required qualifying standards.
However, with the International Paralympic Committee's decision to allow British Swimming's disability performance director John Atkinson to add two additional names to his original squad of 42, came a second chance for Clegg.
Clegg was subsequently added to the roster late last month and will compete in the 100m butterfly as well as the 50m and 100m freestyle at the Paralympics.
And, while his selection may have come late in the day, Clegg certainly isn't planning on any tardiness in the race for the medals later this summer.
"It was a big disappointment when I missed out originally as I had been very close to the qualifying times so to then find out I had got a spot was fantastic," said Clegg, who was joined by Morgyn Peters in gaining a late Paralympic berth.
"I am not sure how it really worked out that there were two extra spots but I wasn't really bothered how it worked out - I am just happy to be going.
"Now that I am going I definitely don't want to go there and not swim well and I believe I can definitely be challenging for a medal.
"I believe if I swim well I can be in the top three and that is what I am going to be aiming for."
Aged just 18 and, by his own admission, set to compete a surprise first Games, Clegg's medal potential remains to be seen however big sister Libby, 22, is a London 2012 star turn just waiting to happen.
As well as her 2011 world 100m title, Libby has Paralympic silver from Beijing 2008 to her name however James admits his late selection may yet cause the family a few headaches in terms of their whereabouts during the Games.
"It is going to be great to be at a multi-sport event with Libby because it is going to be our first," he said. "I used to run a bit when I was younger but we have never been to a multi-sport event and it will be great.
"There is a clash though with my 100m butterfly and one of her events so I'm not sure what will happen in terms of the family that day. I was more targeting Rio in 2016 so to be able to go to London 2012 is fantastic."
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