Apart from it's main aviation functions RAF Northolt is also the headquarters of the British Forces Post Office (BFPO), the postal service of HM Forces.
The BFPO sorting office handles parcels, traditional letters and e-blueys, a secure electronic aerogramme sent to operational units overseas.
Below are 6 items which you may have in your household. If packaged, labelled and documented correctly they can be sent anywhere in the world, although not necessarily by the worldwide postal services.
A = Bleach MSDS UN1791 Class 8
B = Safety Matches MSDS UN1944 Class 4.1
C = Antiperspirant (pressurized) MSDS UN1950 Class 2.1
D = Gloss Paint MSDS UN1263 Class 3
E = Single Malt Whisky MSDS UN3065 Class 3
F = A mobile telephone with working rechargeable batteries MSDS UN3481 Class 9
The cache can be found at N51 3E.X and W000 2Y.Z where
X = (A-D) plus (B-A) minus (C-B)
Y = (A-D)
Z = (P+Q)
Where P is (D+E+F) multiplied by (AxB) and Q is ((A+E) multiplied by F) plus (D+E+F)
Hint: The background image on this cache page is theme of the puzzle, it will not provide you with the complete answer
You can check your answers for this puzzle on GeoChecker.com
Please do not try to remove the cache from the post. The logroll has been adapted so that it can be retrieved while the cache is in the post