Can an ident be abandoned?

What is the copyright status for idents and promos? Are they normally accompanied by paperwork detailing matters relating to the copyright as they are produced for sole use by the TV channel and are not networked or sold? Some idents will contain components from third parties - such as music - but is the usually practice for the TV company to pay a one-off royalty for unlimited use or a royalty payment every time the ident is used?

Therefore, can an ident be abandoned even if the TV company that used it no longer exists?

Yes, look at TVS and Carlton which are no longer own by people in ITV. again the music could be placed on libraries which has happened for BBC2 and STV.

Carlton are still around, they merged with Granada to form ITV Plc.

I thought this was going to be about physical abandonment, like when TV Ark found some Meridian News titles in a skip!

AGain I will repeat

^Carlton is owned by Granada, which is ITV!

Possibly. Imagine the scenario when the tapes containing the idents of a defunct satellite channel are found in a closet in their former premises. Who really owns the rights to them?

BBC Three

This and the entry below the one I linked to probably applies here:
https://www.gov.uk/guidance/ownership-of-copyright-works#works-created-for-an-employer

So I would argue that for example when Lambie-Nairn created the 1999 Carlton look, the fact the company itself now doesn't exist (as above, it merged with Granada to create ITV plc) means either Carlton themselves bought the copyright from Lambie-Nairn at the time (which presumably means ITV have since inherited it), or he/his company retained it. Thinking logically in this particular case it can only be with one or the other, surely? Copyright doesn't just disappear.

This may be an urban myth, but didn't the original Channel 4 idents get a new sound track to avoid royalty payments for FourScore?

There was a BBC One Rythm and Movement idents that mysteriously got a new soundtrack not long after it launched, which was speculated to be a rights problem.

That law is about individuals working for an employer, not company A commissioning company B to produce some work. There will be a contract between the two specifying the copyright situation.

It's the same with radio jingles, the BBC commissioned JAM to create Radio 1 jingles back in the day, and bought a license to use them for a set period of time. When they want to use them for a retro feature or similar they have either get permission from JAM or enter into a new license.

Indeed, I've been told that Chris Moyles got in trouble for using old Radio 1 JAM jingles without permission, back when he did the Golden Hour on Fridays.