The above postcode is for the pub in Marsh Benham village, NOT Hamstead Lock but it is the nearest place with a postcode.
From Kintbury Lock:
Retrace route back to A4. Turn right onto A4 towards Newbury.
Turn right at crossroads signed to Marsh Benham/Hamstead Marshall
Continue along road, over crossroad, then over level crossing.
Lock is west of bridge - limited parking
Remember to tell your crew that they are nearly there - Newbury is only 3.5 miles ahead of them.
Map - Click SAT for aerial view