Third time was the charm for me with this elusive cache! On this and my last visit the coords kept pointing me to the centre of the road, giving me a pretty big search radius. Eventually found it – with the help of properly interpreting the hint – at N 51 46.314, W 001 25.758. Hope this helps anybody else with the same problem! TFTC, and once again for an excellent series.
Attached image is from my second visit, when I was trying to look unsuspicious and like I had a different reason to be hanging around here!