I saw them at the Brisbane store today. They weren't on display but they had some in stock. I love the 4th one in that picture and tried it on. It's AUD$1,650 without a chain. Not bad considering it's quite large - there's a lot of gold there.
It's preeeetty and I want it, but I'm worried it's a bit too trendy and statement-ish and that I won't get much wear out of it over the years. Considering how large it is there are only so many outfits/tops you can wear it with and look good. Hmmm, but I want it.
^ Number 4 was about 2.5 inches long, if that helps you visualise. They're lovely but I reckon they'd be prettier if they were smaller. Take away any clunk factor.
ETA: just looking at the collection on the UK website - there are plenty of mini ones too.
I think they will stay in style forever. I actually remember people wearing jeweled keys back in the 1960s and 1970s when I was in grade school and high school. It's pretty classic. I guess I always think of one of my favorite movies ("The Secret Garden") when I see key jewelry.