This is Watcher's Bridge; a name all but forgotten among the older residents of the village, and harking back to the days when narrowboats still carried goods along the canal. The boatmen believed the tunnel to be haunted by a woman named Kit, and it was said in the the village that a figure was seen stood under the bridge, looking towards the tunnel, watching and waiting. Some had said that they'd seen a woman in a long dress walking down "F'kits Stretch"; the length of towpath between the road bridge and Watcher's Bridges. (The name "F'kits Stretch was not designed to be rude but an abbreviation of "before Kit's stretch") and today periodically dogwalkers say of their pets freaking out along that bit of towpath.
The cache is a large-ish box with a few things in it for geo-kids, and a little medal for the first to find! Keep an eye on children near the water's edge, and watch out for dogwalking muggles and passing boats. You'll need to bring your own pen until I can find small enough biros to fit in the boxes.