The below information has been adapted from a very interesting website on the history of Headington. For more information about the history of Boundary Brook or Headington, please see http://www.headington.org.uk/history/index.htm .
In 1889, Boundary Brook marked the eastern boundary of the City of Oxford, and was the boundary separating Oxford from three neighbouring villages: Headington, Cowley and Iffley. Three of the boundary stones set up in 1892 are still in existence today; two of these are in Headington and the third is in Cowley (on Barracks lane). Boundary Brook marked the eastern boundary for 40 years, until 1929, at which point Headington, Cowley and Iffley were brought into the city boundary of Oxford and became suburbs of Oxford.
Boundary Brook starts just south of the present Cuckoo lane, and runs south down Headley Way. These days it starts underground, but up until the 1930s it was in the open, with steam engines refilling their water from it. The brook crosses the road at the point marked by the boundary stone, the point at which Headington and London Roads meet (hence the change in name here). The brook then continues underground, under the back gardens of residential houses to the east of Valentia Road, crossing Old Road half-way between Valentia Road and Highfield Avenue, finally surfacing after a short bend to the east. Interestingly the brook was piped underground for this section (alongside Valentia road) in the 1980s for health and safety reasons.
After surfacing, the brook runs south in-between Oxford University’s Old Road Campus and Mileway Gardens, passing underneath Roosevelt Drive. This part of the brook is currently part of the “Boundary Brook Wildlife Corridor”. The brook continues south past the Churchill Hospital and then turns south-east running along the edge of the Golf Course. After meeting Lye Stream it makes a sharp south-west turn into Cowley, running down and under Barracks Lane. The brook then goes underground again near Marsh Lane, resurfacing on the south-west side of Cowley Road. Boundary Brook then continues towards “Boundary Brook Nature Park” by running under Rymer’s Lane and along the north boundary of Florence Park to Iffley Road. After passing the Boundary Brook Nature Reserve, the brook makes its final journey to the River Thames, reaching it just south of Donnington Bridge.
This cache will take a path that runs in-between the Southfield Golf Course and a road around Churchill Hospital. You are looking for a micro container. The closest parking is the Churchill Hospital paid carpark (Public Carparks 2 or 3). Or walk through public footpath from Lye Valley, an SSSI. Though be prepared for steep climb just below entry to hospital site.