Just to advise, for those of you who haven’t already discovered this, that Cookham Lock is currently not operational unless the lock keeper is on duty as a result of a major software issue. So currently the lock is only operational between 9am and 4pm with the exception of lunchtime, between 1pm and 2pm. The notices do say that the lock can be used manually (ie winding) after 10pm and before 7am but whether this is in fact the case has not been tested (surprisingly!!)
It could be the case that the lock remains this way until May some time. As and when I receive any further information I will let you have an update!