An alternative to mine, with a bit more of a climb, is to go via Elmdon.
So turn R at the T-Junction onto the B1039, then first left. Climb up Essex Hill into Elmdon. Right at the top of the climb (I think there's a pub there) probably signposted Ickleton.
Then drop down the hill, straight on over a crossroads. Over the M11 and first left shortly afterwards. You then come into Duxford from the South but continue on the road (i.e. don't turn off) which drags you to the right of a grass triangle in the road where the other route joins up.
An alternative to mine, with a bit more of a climb, is to go via Elmdon.
So turn R at the T-Junction onto the B1039, then first left. Climb up Essex Hill into Elmdon. Right at the top of the climb (I think there's a pub there) probably signposted Ickleton.
Then drop down the hill, straight on over a crossroads. Over the M11 and first left shortly afterwards. You then come into Duxford from the South but continue on the road (i.e. don't turn off) which drags you to the right of a grass triangle in the road where the other route joins up.