This is the bonus cache for the Historic Chippenham Adventure Lab. The posted coordinates are for a suitable pay and display car park, the final is NOT at the posted coordinates.
When you have completed the Historic Chippenham Adventure (link to the Adventure Lab), you can get the coordinates from Certitude below. The adventure can be completed in any order but you need to use the answers from the Adventure Journal / completion statements in order. The correct order is ABCDE.
Click on the Certitude link below and enter the numbers represented by ABCDE to get the bonus coordinates.
You can validate your puzzle solution with certitude.
Unfortunately the certitude page has gone faulty so this formula is an alternative way to calculate the final location: N51 27.(B+C) B (3xB) W002 06.(E-D) B (B+D)