Walking to work yesterday in London. Was stopped by two very confused Irish women who were standing outside building numbers 12 and 14. They said they were looking for number 15 and couldn't find it anywhere, could I help? It's not completely unusual for building numbers to be a bit eccentric round here so I puzzled for a bit and then ended up saying, well if it's not on the other side of the road then I'm just not sure, sorry. They looked at me astounded and asked why it would be on the other side of the road? I explained the odd and even system and they went on their way to the correct building. I'd never thought about this before- are we the only country to have this numbering system?