Forgot to cancel? That really stinks!!
I hope you made a personal connection with his PA/Secretary and got HER assurance that he will reschedule your interview.
She/they are the gatekeepers and if you flatter/make them indebted to you, you will get to the boss quicker!
PLUS...
If Sky is like all the other BIG companies I've dealt with you will be able to get your expenses back from HR if you were invited for interview!
DO IT! (or at least try)
Good luck mate.