Has anybody ever bought a house not on the market?

I'm sure I've read a thread about this somewhere, but after two days of searching I can't find what I want.

We bought a duplex half about 18 months ago and would really like to buy the other half. The problem is that it isn't on the market. It's a mirror image of ours so I know the floor plan, but apart from being told that it is original condition (ours had been renovated), I don't even know how bad or good it is inside.

I guess my first step would be to find out who owns it which I think I can get through our local council. I can't just drop something in the letterbox as the property is tenanted.

Then what?

If I write a letter how would I word it without sounding desperate. I'm not, just very interested.

Any clues, hints or tips much appreciated.
Hi Minx,

Do you mean this link?:

As for the letter, something like this?:

We own the other half of the duplex next door.
If you are ever interested in selling we might be interested in buying.
Can't promise anything but here's my contact details if you want to have a chat about it, either now or some point in the future.

Who knows? You can only ask.

How did you find that? I tried forum searches, google searches, everything I could think of.

You are the search guru, I bow to your superiority! :D
That's possibly the least logical search string I've ever seen ...

It is man logic :)

I know I was a poster on the thread, so "propertunity" would pick up my name as the poster.

I kinda suspected it was something like a letter box drop that I (or others) suggested - hence the term "letterbox".

My gf was looking for a house. At a garage sale the tenant mentioned that the owner was thinking about selling.
I contacted the owner and arranged a private sale for my gf.
No agent involved and I think she got a reasonable price.

About a month after she moves out of my house into her house then she dumps me. Problem is the house I helped her buy is 20mtrs from my house. I can see into her lounge from my kitchen.

Not too happy about that:(

Oh well...