Can you identify some of the larger rivers in England (Eng), Wales (Wal) or Scotland (Sco). They all have a length greater than 20 miles (32km).
One of these rivers is made up from two names which are effectively a continuation of the same river so the total length is used. Either name will be accepted.
True, the Cam wasn't on the list as its upper reaches are sometimes referred to as the Granta, though Cam is used interchangeably. Regarding the Weaver, it was probably missed as I was considering just the Weaver Navigation. Both now added, thanks.
Also River Weaver in Cheshire is over 50 miles long