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Comment by jfk13 | Hacker News Reader

I'm aware that "house number + postcode" is often sufficient to uniquely identify a property -- it works for my house, for example -- but I've wondered if this is always the case. When I enter a postcode into my satnav, it sometimes offers a choice of several street names, which seems to imply there might be duplicate house numbers within the single postcode. But I've never tried to confirm this -- do you know?

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It's not always correct, no.

Fortunately there's another identifier - the Unique Property Reference Number (UPRN) - that exists to, well, uniquely identify every property in the UK.

Currently it's proprietary but from July 2020 it will be available for use under the Open Government License.[0]

[0] https://mhclgdigital.blog.gov.uk/2020/04/02/unique-property-...

The UK postcode system is not some magic hash that can resolve to a street name. Instead it’s a database maintained by Royal Mail that’s updated when a new postcode or street is created. This would explain why your sat-nav doesn’t know about newer addresses as its database hasn’t been updated.

By "number" I meant "name or number", since some buildings don't have a number. A flat number is obviously also necessary if applicable.

A previous discussion on this, in 2013, tried to give some examples. None of them seem to break the rule, since "Pleasant Cottage" and so on are building names. If there's a counterexample, Wikipedia should be updated.

https://news.ycombinator.com/item?id=5625027

In the US, that's actually kinda surprising to me. Even in the suburb where I grew up, where there's no obvious overall grid system and instead the streets tend to meander around, parallel streets in the same neighborhood tended to share a lot of numbers.

I think they are giving all houses a number now, most houses around me (south west uk) have a name and a number now, where they all used to have names.

My house has a number, but for some reason it's listed under the "name" of my house - no end of confusion.

Not always. At my old postcode someone had recently built a block of flats not quite large enough to get its own postcode. The postcode also contained an older block of flats and some houses. We were flat 9 but the postcode contained two flat 9s and a house number 9.

Yes I had an address that had a duplicate.

I think the other address was supposed to have an East before the street name, but when they left that off I got (some of?) their mail.

Should have figured out my +4 and tried that.

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