When using a satnav with a UK postcode it's useful to know that the device will probably use the 'median coordinates' of all addreses with that postcode. That's what the Post Office publishes. 'Probably' because it may use the nearest point on a road - don't know.

In a street of, say, 10 houses with the same postcode that should be near the middle of that row of houses. But in the countryside it could be some distance from the address you're looking for, and in the middle of a field.

Something to bear in mind as you drive to a rural B&B or village hall in the dark!

Senoufou: Google for the Great Trigonometrical Survey of India, carried out by a Mr Everest! And here in the UK you can adopt a triangulation pillar - aka 'trig point' - if there are any left.