Summary
The cache is not at the published coordinates, but you are likely to need to visit them. A few good parking spots are suggested in case you're coming by car; there's also lots of on-street parking throughout the surrounding housing estate.
The geocache itself is less than 300 metres away and is easily walkable.
History
During the Second World War, this was the site of RAF Stanton Harcourt, an auxillary airbase to nearby Abingdon airfield. Among the operations to take place at RAF Stanton Harcourt was the training of aircrews in the use of the Blind Approach Beacon System, which facilitated night landings in blackout conditions or even during heavy fog.
The system consisted of two parts. On the aircraft, a Rebecca unit (pictured below) would send a radio signal to a ground-based Eureka station, which would detect the angle from which the signal was received and respond with a signal that indicated the direction in which the pilot ought to steer in order to remain on course for landing.
Radio-based navigation technology has come a long way since the 1940s. But these kinds of early "beam" navigation systems used by mid-century airoplanes and ships paved the way for future radio navigation systems... including the GNSS (GPS) signals that you'll use to find this geocache.
There's little evidence of this former airbase, but if you look around carefully you'll find original garages, the remains of bomb shelters, and a few other remnants. And in a nod to the site's history, the new housing estate names its streets after some of the aircraft that were stationed here.
Finding the cache
At the published coordinates you'll find a metal plaque commemorating the men and women who served at this site, attached to the restored former water tower. Use the information on the plaque to answer the questions below and substitute the answers into the coordinates:
The cache is at: N 51° 44.ABC, W 001º 23.ADC
- A: Find "Archer": there's a word in brackets after their name. How many letters does it have?
- B: How many people's names appear directly above "Kelly, B W, Sgt"?
- C: Find the sentence beginning "known to have died in action". How many letters does the last word have?
- D: How many columns are each set of names separated into?
- Checksum: if you add up A + B + C + D, the last digit of your answer will be 1.
You're looking for a black metal tube. Please take care to put it back into its hiding place upside-down and with the identifying label facing away from the path, to keep it as well-hidden as possible.