key replacement

Can anybody tell me how to get a replacement door/ign key for a 10 year old Corsa?
Yes....another key should always be available, but the spare has been lost in a house move!
Cheers - Mick.

I enquired about this a couple of years ago - shoe repair shops (with key cutting) usually do this - they need a code from the chip in the key - but it costs about £25 per key!