I was curious about this so I googled it...it seems as though they're two different British actors both named George Maguire, although when I google the term "George Maguire Billy Elliot," the picture on the far right side of the screen is the same as the man when I google "George Maguire Sunny Afternoon." It seems as though even google is confused about it. But looking for pictures of the George Maguire from Billy, although he was younger then, he doesn't look like the same man. The key clue that they're different being the Sunny Afternoon website's bio for George doesn't list him as being in the original cast of Billy Elliot. So all in all, this a confusing subject.
"Contentment, it seems, simply happens. It appears accompanied by no bravos and no tears."