Lighten our Darkness Mystery Cache

The above coordinates are for a random place in the River Thames just North of Gravesend. You do not need to go there to work out the coordinates of this cache. Just work out the puzzle below.

So this winter like most we have had Strictly Come Dancing to lighten the Dark Winter Months. This Year we saw a Good Win for the favourite on the busy Channel. Foxtrot x 3!!! - Wow!

Consider A to E where:

A = N50 03.616  W006 04.357

B = N49 54.459  W002 53.744

C = N50 24.538  W000 00.095

D = N51 09.355  E001 47.122

E = N51 01.286  E001 23.897

Cache can be found at:

N51 26. E C (C/D)

E000 23. (A-E) (B+(C/D)) (B-(C/D))

You can check your answers at:

Cache is a green magnetic torpedo tube