OK.. According to my accurate mapping instruments.. (

) if we follow the route Sandy, Everton, White Wood, Abbotsley, Eltisley (turn right just before the village), Great Grasden,Waresley [Coffee stop], Gamlingay, Mill Hill, Potton, Sandy, it will be exactly 35 miles.
That gives though a bit more for Chris and Jacqui as they will have the extra milleage of travelling from and to Bedford.. There is a short cut that takes us to 30 miles approx and might be a good idea as it would make it a 40mile ride appox for the couple..
Up to you guys!!