Introduction
See Green Chain #1 for cache trail introduction.
Route
Keep heading down Park Avenue.
Description
Park Avenue is presumably named for the large country estate that occupied this area in Victorian times. London Lane marked the Southern boundary of this estate with Plaistow Lodge being the manor house (now the main building of Parish CofE School).
At the junction with Kinnaird Avenue (named for Lord Kinnaird a former owner of Plaistow Lodge) you'll find a large green pipe and there are a few others around in the area. I spent ages assuming these were old abandoned lamp-posts or similar before finally discovering that they rejoice under the wonderful name of stink pipes! I've read that they form part of the Victorian sewerage system, obviously designed to take the smell well above the height of human nostrils. Though I must confess I don't know how this ties in with Park Avenue dating from well after Victorian times.
The Cache
You are looking for a (non)magnetic key safe.