For anyone struggling with trousers for children in cloth nappies try H&M. I just bought DS - 20 months a lovely pair of cord from there for £7.99.
They have a popper and zip fly (easy to get on), seem to be cut generously AND have an adjustable waistband exactly like maternity trousers so they fit nice and snugly at the back!
Also full marks to H&M for putting name labels in the clothes you can just write on!