"It's been done about as well as it can possibly have been done," Philip said. "I feel my books have fallen into the best possible hands.
"You have to make sure every bit is visible from the front of the audience to the back. That is very different to my novel.
"To read my books from start to finish takes about 35 hours - a lot of it had to go!"
There are some key characters who just had to be left out ( we won't spoil it for you!) and the story had to be shortened.
And the cast are older in real life than the characters, but Philip insists this works. "It's brilliant, it's perfect," he said.