Population or voter equality was still a new concept, and not really prioritised. Most parliamentary boroughs still had their own constituencies, particularly in Scotland, and there were still very few suburbs, so you get lots of tiny urban constituencies (this is also true in 1918-35). The redistricters were mandated to separate urban and rural areas as much as possible, as part of the Liberal-Conservative compromise to pass the Act. County and borough boundaries were very strictly respected. Many ancient county boundaries were still in place, particularly around Worcestershire (
Wiki).