I think "women of the peerage" here means daughters of peers not peers themselves. Only the eldest brother would sit in the House of Lords and only after their

I think "women of the peerage" here means daughters of peers not peers themselves. Only the eldest brother would sit in the House of Lords and only after their father died. It was very common for a son due to inherit a peerage to go in to the commons before they inherited their title. Once a title was inherited one could only sit in the House of Lords until Tony Benn.