How does copyright work on sound recordings?

[jojopin66]

How does copyright work on sound recordings? If I found a unreleased recording of somebody singing a song I'd never heard before, who owns the copyright - the performance and the publishing? And what if I didn't know when it was recorded? Or who had written the song? Or who was performing the song? I'm not sure how long copyrights last. And could I go about claiming copyrights if I wanted to?

(I'm in the UK, but it may be different in other countries - still somewhat interested in what happens there too)

CR vests with the creator & after his death with his or her estate for 70 years. This can be complicated if the CR has been assigned or licenced.

Can you prevent your artistic works being released in the future? Can you put in a clause in a will to stop beneficiaries ever releasing them (with the assumption you've not signed any professional recordings/publishing/licensing deals and are just an amateur)? Or once you're dead, can your beneficiaries do what they want with any of your creative works anyway? Could they still be released hundreds of years in the future if they were ever discovered? Sometimes what were ostensibly private diaries like Anne Frank or Samuel Pepys get published.