Are you meaning smart shooting trousers, like breeks, or longer/regular trousers?
Mrs G is petite, though these days a size 10 rather than a size 8. For picking up she often goes for larger children’s sizes rather than specific women’s trousers. Ridgeline have been good for both trousers and jackets. Schoffel do some nice ladies kit, though it can be pricey.
It’s worth keeping an eye out on the websites of John Norris, William Powell, New Forest Clothing and similar, as the small ladies clothing often ends up in the sales.