It used to be the case that at each point where a road breaks through the boundary to enter a parish, a cache had been placed. In the log book for each of these caches a piece of information existed which could be used to locate a bonus cache: The Interior for Northill and The Interior for Old Warden. These caches have now been archived.
Northill parish has two websites: one for the Parish Council and a Community Information Web Site. The parish is home to the Ickwell May Day festivities which have been taking place on the green in Ickwell since at least 1565.
Old Warden parish has a website at https://oldwarden-pc.gov.uk/. The parish is home to the Shuttleworth Collection which is an aeronautical and automotive museum located at the Old Warden Aerodrome.
The Shuttleworth Collection and airfield are actually just inside Old Warden parish (the boundary runs along the road between Old Warden and the A1) but the air shows that take place on a regular basis over the summer has planes zooming, puttering and screaming over Northill parish as well. If you are looking for this cache on the first Sunday of a summer month, you may find quite a few cars parked at the side of the road, watching the show without paying the admission price!