Use the additional waypoints to locate the following...
Salt Marsh
A = How many birds are pictured? (Don't forget the wren!)
Industry
B = The number on Blackstock Street for William Gossage & Sons.
The Marsh
C = How many birds are pictured?
Shipping
D = Telephone : Widnes 22D1/2.
The cache can be found at
N53 2(C-1).(C+D)(A-B)D
W002 4(D-C).(A-C)(A-D)C