Magnetic black 1.5ml vial. Note the GPS reception was not great here so use the hint.
Update
Because this is a busy area I would rather people found it than get spotted looking (it has already been muggled in the first few weeks of listing). So I have included two spoiler images, please take a look. Not only will it give you a very fast find, but will also show you which way round to replace the cache and help prevent future muggle attacks!
Thanks.
About the trail
This trail takes its name from the fact that this is a walk my Scouts have done (far too) many times on a Wednesday night.
The walk is around 4.5km (2 3/4 miles) along footpaths and bridleways and should take about 2 hours. The terrain is easy going, with no major hills. Just the classic gentle rolling fields of Hertfordshire. The paths can get muddy when wet, as you would expect with this kind of country side walk, so appropriate footwear is advised.
There are 17 caches in total and the route takes you past one extra cache from a different series (spot-8). Most of the caches are 'log only', so you will need a pen. Also I would recommend taking a pair of tweezers as some of the logs might be tricky to pull out.
There is one larger cache in a lunch box sized clip lock Tupperware container. This one contains swaps and has plenty of room for TB's.
Every cache has a good hint and should be an easy find.
Enjoy!