  We drove past it on our way back from stanstead the other day... 9a is the junction with the A1301, A11 and M11 (Spur) at Stump Cross, whilst 9 is the limited access junction between the M11 and it's spur which becomes the A11.  Did you know that the southbound stretch from Duxford (Junction 10) to Stanstead (Junction 8) is the 2nd longest stretch of motorway in the country (after the M26) with no access to off sliproads at junctions? - 