I've always got my ds the majority of his clothes from Sainsburys but although he's not particularly tall (around 104/105cm) or skinny, I e found that he needs age 2-3 (or 3 depending on the department) for the waist size but a 3-4 (or 4) for the length but even that'll be too short soon.
Does anyone else have this issue and where do you recommend for small boys trousers that don't cost the earth?