Its ambiguous name is presented frankly as "Cam or Rhee" even by the Ordnance Survey, though the Rhee is one of two rivers claiming the famous name "Cam", the other being the River Granta. The two unite just north of Hauxton and below that point the united river is by tradition known as the Granta until Silver Street Bridge in Cambridge and the Cam below that bridge.
The Rhee rises at Ashwell in Hertfordshire, just off the High Street (at Ashwell Springs). From here it runs north towards Eyeworth, forming the border between the counties of Hertford and Bedford and then those of Cambridge and Bedford before entering Cambridgeshire fully at Hook's Mill. This latter stretch has been artificially straightened, but the original course remains the border. The river then flows eastward for 12 miles through the farmland of southern Cambridgeshire.
Passing under Ermine Street (the A1198) at Wimpole Lodge, the Rhee (or Cam) soon crosses through a long, thin strip of the Wimpole Estate (owned by the National Trust) and bridged by a footbridge: this strip forms a two-mile vista south from the gardens, with an octagonal pond in its midst, close by the river.
Below Wimpole the Cam (or Rhee) passes north of Whaddon and Meldreth to reach Barrington, the first village actually on its course. For much of its length the Rhee has formed the parish boundaries hereabouts, and at Barrington it divides this parish from Shepreth and Foxton to the south.