Our first find was the original Pillar To Post, a multi-cache which began at Norman Cross and ended up at Holme Fen Posts. As we had no GPS or even a smartphone back then, we worked out each stage by collecting the numbers and driving home to look up the resulting co-ordinates on Google Earth! You should find it a little easier to find this anniversary cache! 
We'd like to take this opportunity to say thank you to all the lovely friends and new people we've met through caching - and we're not stopping yet!