You need to collect some numbers at the two clue waypoints given below. (There used to be three clues but the plaque for one of them has been removed.) Each letter represents a single digit value (0-9) that you will be able to find written on something:
Waypoint 1 (N 52° 13.4664 W 000° 32.9137):
Fill in the numbers: [A] SV [B][C]
Waypoint 2 (N 52° 13.5209 W 000° 33.1130):
In what year was the Earthworks first recorded on a map: [D][E][F][G]
The co-ordinates of the cache can be found by substituting the numbers for the letters below:
N 52° 13.[G][D-C][A-B] W 000° 33.[C][G][F]
The cache is in woodland so it may tax your GPS receiver if the leaves are wet. It is a small Lock 'n' Lock container which is NOT on the site of the monument, there is no need to dig to find it. Initial Contents were: Log book and pencil, Lots of Geocacher's creed cards, 2 Travel Bugs, various small toys, badges, First to Find Certificate, and Geocaching Badge,...