You need to find the location of the four sculptures, and then determine the mean location of the four.
To assist with erroneous GPS readings, I am assuming the Northmost is N 51 xx.xx6, W 0 xx.xx5, the Westmost is N 51 xx.xx7, W 0 xx.xx0, the Eastmost is N 51 xx.xx6, W 0 xx.xx1 and the remaining one is N 51 xx.xx2, W 0 xx.xx6.
Once you have an average, add "S 0 0.158, W 0 0.211" for the cache location (updated 2014-02-16). There is a geocheck.
When you have found the right sculptures, the following list will make sense:"Anne, Diane, Elizabeth, Elizabeth, Kathy, Anita".
The cache is a 2l clip-lock box with assorted goodies and a First To Find trophy. Ensure it is well hidden after signing the log.
(The geocheck is for the mean position, not for the cache location.)
Good hunting. You may also be interested in my other caches.