Why won't Siri recognise my home address? How on earth do you get Siri to remind you to do something when you arrive at a location in iOS 6?  It worked fine in iOS 5 but I've never got it to work on iOS 6 - it just always seems confused about what I'm trying to do. What is the correct syntax?

Siri has been pointed at my own contact record in settings and that record contains my correct address under "home".

EDIT:
I've noticed that siri also can't answer the question "How do I get home". It just says "I couldn't find an address for Nick - home". 

Oddly, if I totally delete my "home" address and ask "how do I get home?", Siri says "I don't know what your home address is, Nick. Tap your name if you'd like to add it." and shows me my contact record. This is different to what it does if my home address has been set on my contact record.

The fact that it behaves differently if the address is keyed or not makes me think it's definitely finding my home address on my contact record, but for some reason doesn't want to use it. If I tap my address on my contact, it shows my correct location on the map so it's geocoding it correctly to coordinates, so I really don't see why this doesn't work.

This is what's happening:
OK I've found out the answer myself.

It turns out that although the Maps app can geocode (find the location of) my address, Siri can't. It must be using a different geocoder to the Apple Maps app. 

After much faffing, I found the easiest way to fix this is to drop a marker on my house using the Apple Maps app and then add this to my own contact record as "home". This fixes the problem and allows Siri to know where home is. However it then means my address is incomplete if I use it for other purposes or in other apps). The only way round this seems to be add it back and tag it as "address" (NOT "home") as a second copy of the same address. Really messy.

Clearly this is a bug in Siri which will hopefully be fixed one day (I won't hold my breath). I don't recall having this problem in iOS 5, so I think this was introduced in iOS 6.