William was awarded the opportunity after a recent test at Donington Park on British Champion John Reynolds' Rizla Suzuki GSX-R1000 when he impressed the team with his speed and natural talent.
Son of Robert and nephew of TT legend Joey, William is a regular podium finisher in the Irish 125cc Championship. At 19 he is heralded as one of the best young up and coming racers in the UK and belongs to the first family of motorcycle racing in Northern Ireland.
"This is a dream come true for me," explained William. "Rizla Suzuki is the Championship winning team and it doesn't give out test rides to just anybody. When I was invited to test the bike it was a fantastic experience. Then when I was invited to race it against some of the best riders in the world at the Castle Combe Grand National, I was ecstatic.
"Thank you to Rizla Suzuki for giving me this opportunity. I plan to use it to show what I am capable of and as a stepping-stone for my racing career. It isn't going to be easy as I don't have much experience of riding a Superbike. The Rizla Suzuki is mighty quick and it'll take some getting used to, but I am hoping to have another test on it before the race weekend."
William will be up against the cream of the British Superbike riders in the Castle Combe Grand National - with riders the calibre of James Haydon, Michael Rutter, Karl Harris, Tommy Hill, Sean Emmett, John McGuinness and Jonathan Rea already on the starting list.
Rizla Suzuki's James Haydon said: "I watched William during the test and he showed a real turn of speed despite his lack of Superbike experience when he rode the Rizla Suzuki.
"He would go into a corner too fast and miss his apex, but the following lap he would be pin sharp, which shows he is thinking, safe and talented. He is certainly a star for the future and I'm looking forward to racing alongside him at Castle Combe and giving him all the advice I can."
JR was also watching William at the test. He said: "I will do whatever I can to help William advance his career. Rizla Suzuki has had an eye on him ever since 2004 when the late Davy Wood asked us to consider him as a talent for the future. From what I've seen, Davy was on the money and William has the capacity to be a Champion in this sport. He certainly has the genes for racing with the Dunlop name. It won't be easy, but he has a great opportunity to show what he can do by racing my Rizla Suzuki at Castle Combe and I'll be there backing him all the way."
The Grand National takes place at Castle Combe near Bristol on the weekend of July 30th and 31st. For more details visit http://www.castlecombecircuit.co.uk/.