Great news following the message below, the road is now fully re-opened ( from Thursday 25th Oct) and access is open from Sandy and Potton again.

The B1042 has just been closed while road works take place between the reserve and Sandy. We had no prior notice of these works, so apologies we weren't able to give any advance notice.
Please plan your route to come via Potton while the diversions are in place.
The contractors inform us they should finish by Wednesday

Latest update; the road re-opened at 3pm today, but we expect another closure for at least part of the day tomorrow and Wednesday this week.