Sydenham to Crystal palace, just a couple of caches to fill in the area.
A simple multi to continue the series, there is a green sign, number of letters in specified word.
A = 1, 1
B = 2, 1
C = 5, 2
D = A/C
E = B*C
N51° 25.ABC W000° 04.DEC
Checksum - 42
Park either side of published co-ords by 100M. (The gatso is set at 20MPH)