1,2,3 make a nice walk; 4 is separate; 5-8 also make a nice walk.
Being old, I remember when the M25 wasn't there. The picture was taken in 1985 from memory somewhere near the coordinates above (which aren't where the cache is!), when we went for a walk along the Surrey section between Reigate and Leatherhead just before it opened.
This series of caches is dedicated to that memory, and takes you to places near the M25, of which you are probably not aware as you trundle past.
Assume N 51° 1B.A+B G A W 000° 1E.D+G G C