If you can get it to fit, there shouldn't be any problem. Sometimes it can be tricky to mount racks and other items on old Raleighs, but the bikes are solid.

I had a different child seat on my Raleigh, a Britax Roemer Jockey. It was very difficult to swing my leg over the top bar without knocking into the seat or my daughter. Step throughs are better for this kind of hauling.