Coaches, wagons and locos that are part of sets don't have their own R number, so the R number is the same as the set number. What this means is unless someone has split a set and is selling the carriages you may find it difficult to source the exact set items on their own (as the carriages have probably got unique running numbers that don't match any carriages sold separately). If you bought the set as a split, then the original owner probably didn't need the track and controller.