Green Cheltenham Mystery Cache

The cache is not to be found at the published location.  The cache is a nano - please bring tweezers and a pen or pencil to sign the log.  

Cheltenham has many green spaces in or nearby.  Your challenge is to identify the green spaces shown below and order them from north to south.  For avoidance of doubt, images are ordered by their centres.  A simple sum will then get you to the cache location.

A
B
C
D
E
F
G
H
I
J
K
L

Fill in this table with the letters beside the images in order from the most northly image to the most southerly image:

The cache is to be found at N 51° 53.XXX W 2° 5.YYY' where XXX is the result of the following expression A.(B-C)+D.(E-F) and YYY is the result of G.(H-I)+J.(K-L).  "." represents multiplication.