I had 2 keys with my car which was bought from new around 13 months ago. I lost one key about 5 months ago, it just disappeared off the key ring one day. Yesterday as I locked up my car my remaining key fell off. Luckily I was alerted by someone passing by.
On closer inspection the bit where the ring goes has come apart. So the ring just slips out. This is what must have happened to the first key.
Would it be reasonable to assume it's a design fault and ask Ford for a free replacement? A new one will cost in the region of £350.