Bordering on the ridiculous Mystery Cache

The posted coordinates are for a pub. To determine the whereabouts of the cache, you'll first need to find three geographically interesting locations.

If the (decimal) coordinates of the missing locations are:

1. ±A.9035, ±B.4535
2. ±C.4370, ±D.9360
3. ±E.1500, ±F.7625

then the cache can be found at:
N 51° 17.X W 000° 35.Y
where X = ((A+C-E)*10)+27
and Y = ((B-D+F)*3)+16

Edit: As often seems to happen, real-world events have conspired to spoil a perfectly good puzzle! As of 1 August 2015, number 3 has become a footnote in the history books. I don't think this makes the puzzle any harder … or easier.

Congratulations on the FTF to =Andy_R and Kermit&Co.