DTD2 is very tall and very leggy.
She needs black school trousers. I very much doubt childrens 'long' trousers will be long enough (last years m&s long are about 2-3" too short, but open to a retailer I have missed (not BHS, Tesco, Sainsburies, Asda).
It is very likely I will have to go for an adult size 6 long, but I am struggling to find a style which isn't too tailored and 'officey' or too casual. They just don't look like school trousers. They also need to be a style where I can alter the waist as she is exceedingly skinny and adult sizes don't have adjustable waists.
Budget, as little as possible as I will need to be 2-3 pairs.