The cache is not at the listed coordinates. In order to find the cache you will need to go to the Little Bridge at the listed coordinates and obtain two pieces of information.
A = Number of vertical posts that support the horizontal rails on the eastern side of the bridge.
B = Number of vertical fence panels just to the east of the bridge that have been cut at an angle.
Check: A + B = 14
Now use the following formula to find the cache:
N51 25.B77 W001 32.(A+2)15
The Little Bridges series was started by Stanthews in 2009 to highlight small footbridges in remote parts of Wiltshire. Since then the series has been expanded by others all over the country and starting to spread fast, Damian from Winter Foxes has created and updates a list of cachers who has found 10 or more little bridges and can be found here, if you would like to add to the series, please contact Stan on stanthews@aol.com and he will give you a number for your bridge, to qualify, the bridge must be a foot bridge too small for vehicles, please make sure your title exactly matches “Little Bridges # xx then name” including spaces so it will get picked up and added to Damian’s list.