They are really well fixed once on. There's no way they would come off accidentally. You have to pull them apart. Keep an eye on Liberty, as they will sometimes go on sale. Definitely worth saving up for, they are solid and weighty.
I got mine a while back. I had a post-divorce splurge and treated myself. They are my 'free at last' celebration present. I went to the showroom off Oxford Street, his stuff is stunning.