Subject says it all If I find ones long enough age 3-4 such as hennes, they are huge on the waist and fall down. If I find some skinny enough mini mode, they aren't long enough and sit half way down her legs! HELP she refuses to wear jeans and I don't blame her as they have to pulled in so much at waist they dig in!
I have a tall and skinny and extremely long-legged 3-year-old. The best tights for her come from the Finnish brand Vendi. Size 90 cm are perfect although she is currently 100cm and about 13-14 kg. You can get them here (they have currently a 3 for the price of 2 offer, 90 cm is available in pink only), or email the shop owner email@example.com, I'm sure they speak English and shipping to UK cannot be a big deal.
H&M sizing is for short and tubby children IMO. Never a great fit for my DD.