Postcodes are a lousy navigation mechanism in rural areas. Even if your navi has been updated recently. And even Feral’s mate who provides the server for this site only updates his GB postcode database every 3-6 months when a new version of CodePoint Open comes out.
What you should have done, you peasant, is give a latitude and longitude like a grown-up. Lat and long works on every navi, and on paper maps too.
(Mapcode is very nifty but hardly anything uses it.)
Just one teeny weeny problem with all the clever systems: nobody knows them. “Hardly anyone uses it” makes it a lousy system, not a nifty one, if you want people to know what you are talking about.
Personally, I do know my postcode, having spent a year or so having to look it up at intervals before I learnt it; I have no idea where this house is for any of the other systems, not even lat and long; nor do I know how or where I would find out the exact lat and long of this house. Nor, to be honest, is it likely that I would remember them if I did manage to find them.
That’s why I (reluctantly) wasn’t recommending mapcode, Fishers.
But you can look at Google Maps (if you must) or OpenStreetMap or Bing Maps or wikimapia or pretty much any other map provider, zoom in on the place you care about, and read off the lat and long from the URL. (For example I might zoom in on https://www.openstreetmap.org/#map=17/52.21371/-1.98077 and tell someone “52.21371, -1.098077”.)
It assumes that if you’re giving someone directions to somewhere, you care enough to make the tiny bit of effort needed to give them a location in a universally recognised format rather than something that may or may not be of any use to them. (E.g. what3words, which is great fun but horribly proprietary and can’t be used at all with paper maps.)
Yes, I realise that most people aren’t prepared to make that tiny bit of effort, but that is because they are Wrong.
I’m inclined to agree about postcodes, though; they cover too large an area. Just drove all the way to Belfast, only to be let down at the last few hundred yards. “Turn left at the traffic lights” is all very well, until you realise that where you were trying to get to was on the left past the lights…