Stage 1 (posted co-ords) - Number 1 pub name in the UK!
There is a post box near the pub. You need the numbers indicated. The post box is number RH1 abcQ
Stage 2 - Another Post Box, Number RH1 def
Stage 3 - Number 4 pub name in the UK!
Across the road is a phone box. You need the phone numbers last six digits. ghijkl
Final hide is at N51 (e&f).hh(i-j) W000 00b.hd(a&c)