START (GR TL584578) on A1304 at north end of lay-by which is 0.7 miles north of Six Mile Bottom Cross roads proceed north on A1304 to Stetchworth RAB.
Circle RAB to re-join A1304 and then stay on A1304 to join A11. Stay on A11 to take slip to Four Went Ways. To RAB (12.115) start Circuit A.
Circuit A.
Take 4th exit (0.203) on RAB to re-join A11 northbound . Continue on A11 to take exit to Six Mile Bottom (4.946). Cross railway level crossing and continue on A1304 to Stetchworth RAB (9.325). Circle RAB to re-join A1304 and then stay on A1304 to retrace to join A11 (13.676). Continue on A11 to slip road to Four Went Ways RAB (18.407). At entrance to RAB (18.574) End of Circuit A. Repeat up to 2 times.
Circuit A to B.
Take 2nd exit from RAB (0.059). Continue on A11 and keep in left lane to join A505 (0.692). Continue on the A505 to turn left at the Sawston RAB (2.774) onto the A1301. Stay on A301 until the entry to the Welcome RAB (4.609) start of circuit B.
Circuit B
Circle RAB to re-join A301. Continue on A1301 to turn right at Sawston RAB (1.869). Stay on A505 to join the A11 (3.954). Stay in left lane on the A11 to take the exit to Four Went Ways RAB to turn left at RAB onto A1307 (4.621). Continue on A1307 until 2nd RAB (8.276). Circle RAB to re-join A1307 until Four Went Ways RAB (12.016). Take 3rd exit to join A11 southbound (12.313). Continue on A11 and keep in left lane to join A505 (12.801). Continue on the A505 to the Sawston RAB (14.887) Left onto the A1301. Stay on A301 until the entry to the Welcome RAB (17.290) end of circuit B. Repeat up to 4 times.
Circuit B to C
Take 1st exit to stay on A1301. Straight over next two RAB’s under the A11. Continue to next RAB (Stump Cross RAB) and take 2nd exit onto B184 (0.602) start of circuit C.
Circuit C
Continue on B184 to Little Chesterford RAB (1.579). Circle RAB to re-join B184 and then continue on B184 to turn left at Stump Cross RAB onto B1383 (3.207). Stay on B1383 until the RAB with the B1502 (8.913). Circle RAB to re-join B1383. Continue on B1383 Stump Cross RAB (14.681). Take 3rd exit of RAB (14.705) end of circuit C. Repeat up to 4 times.
Circuit C to D
Take 1st exit at RAB onto A1301. Go straight over next three RAB’s and continue on A1301 until Sawston RAB (2.337). Take 3rd exit onto A505. Stay on A505 to join the A11 (4.421). Stay left on the A11 to take the exit to Four Went Ways RAB (4.972). At RAB take 2nd exit to rejoin A11. Continue on A11 to Six Mile Bottom exit (9.913). Take the exit to join the A1304. Go over the level crossing and straight on at the crossroads (10.718). Stay on A1304 until start of layby (11.376) Start of circuit D.
Circuit D
Continue on A1304 until Stetchworth RAB (2.881). Take 1st exit onto A1303. Continue on A1303 until Dunsley Corner (8.438). Turn sharp left onto Little Wilbraham Road. Continue on Little Wilbraham Road to go under the A11 and keep going until crossroads (12.089) Turn left and stay on A1304 until start of layby (12.760). End of circuit D. Repeat circuit until 12 hours elapsed.