It is not possible to unambiguously write all addresses in the UK without including the post code.
The post code and door number are the primary key of the data.
A fine example: http://nominatim.openstreetmap.org/search.php?q=high+road%2C... Zoom out one level and you'll see that High Road is surrounded on both sides by High Street. And yes, that is correct.... High Street > High Road > High Street = One road in one very old town.
Crazily if you look down a little further you'll see the Southern High Street (A408) goes East, and what is technically another High Street heads on Southwards.
3 High Streets, and 1 High Road... in less than 1 mile in 1 town.
I was actually looking for the Church Road in Uxbridge that comes off of Church Road, but I think Google Maps incorrectly has both of them as Church Lane.
Here you go: http://nice-map-urls.herokuapp.com/ub5/united-kingdom/englan...
Church Lane coming off of Church Lane. One is the A312, the other is just Church Lane.
Google is wrong on this, they're both called Church Road. And historically they were the same thing, but as it evolved from a way to get to the church to a market thoroughfare one main road emerged and left the other road as a side road. Over time this actually led to both roads being distinct, and with their own door numbering schemes, even though they meet each other.
I find the history of places as fascinating as the history of languages.
I think they were originally separate unjoined streets. But a road was built up the hill, joining them together. I guess people couldn't agree on who should have their houses renumbered.
If manually specifying the address you probably have enough wiggle room to specify which 10 Something St you mean. I've encountered systems online that will try to normalize and correct street addresses to an official format... I could imagine that these would cause problems.
(And don't confuse those addresses with the 10 New Something St, or 10 Something Rd, both of which are only a few hundred meters away.)