In some colleges, postgraduates are members of both the MCR and JCR: for example, at St John's, where the MCR is known as the Samuel Butler Room or at Peterhouse. Most colleges also have an SCR.
At certain universities, postgraduates hold membership in both the MCR and JCR. For instance, at St John's College, the MCR is referred to as the Samuel Butler Room, while at Peterhouse, it holds this designation.  Most colleges also have an SCR.