When the business parking is shut, there is no access to the outside world. (This is the normal situation as far as I am aware). If the car park gates are unlocked outside office hours, suggest that you moor up against the wall away from the wharf.
This view is taken from Fazeley Street bridge, looking in to the basin. The access to the car park from the street is between the wall at the left arm of the basin (by the container) and the old Typhoo factory behind.
There are no boaters facilities at this mooring. (There aren’t even mooring rings, unless they are so buried in the undergrowth that I couldn’t find them – I tied up to the trees)