The cache is not at the publishd location, to find the bonus cache, you should complete the Adventure lab cache, 'Broad Stone's'.
The posted co-ordinates, are for free parking for 2hours Monday to Friday, and all day at weekends.
Mobile app smart link
Use your phone's native QR code scanner to open this adventure in the Adventure Lab mobile app, or share the following URL:
https://adventurelab.page.link/Rpfo
As you complete the lab caches, make a note of the values of the letters A,B,C,D,E.
Cache can be found at.
N 50. 45. A ( E+B )( B+C ) W 001 59. ( D+E )( E-B )( C-B )
Take care & enjoy your stroll.
The Lab caches are wheelchair friendly, but you may need assistance to retrieve the final bonus cache.
Congratulations for FTF to Dorsetgal & Geodog.