Beware though the sizes are very big. DS2 (skinny 7) tried the adjustable waist trousers. We adjusted them as small as they would go, and they were still way too big and looked ridiculous.
I would like better quality/harder wearing trousers for him this year. But the only ones that seem to fit skinny kids properly are Asda. So unless anyone has any new suggestions we'll be back at Asda again this year.