Do actors have rights over the footage? I was recently involved in filming and one of the actors walked out partway though. She has since convinced the other actors to sign a document with her stating that no footage filmed involving them is to be used.

The script was written by the producer and all of the cast and crew were hired on an expenses only agreement. While there is no official contract, the job listing and email correspondence back this up. I have looked up the copyright law in the uk and here is what it says:

According to http://www.ipo.gov.uk/types/copy/c-ownership/c-employer.htm

"Where a written, theatrical, musical or artistic work, or a film, is made by an employee in the course of his employment, his employer is the first owner of any copyright in the work (subject to any agreement to the contrary).  In the course of employment is not defined by the Act but in settling disputes the courts have typically had to decide whether the employee was working under 'contract of service'.

Where a person works under a 'contract for services' he may be considered by the courts to be an independent contractor and his works may then be considered to be commissioned works."

Contracts for service are further defined here http://www.ipo.gov.uk/types/copy/c-ownership/c-commissioned.htm

"When you ask or commission another person or organisation to create a copyright work for you, the first legal owner of copyright is the person or organisation that created the work and not you the commissioner, unless you otherwise agree it in writing."

Given my understanding, the actors have no legal say in the footage, raw or otherwise, only the script writer/producer, director and cameraman have a stake. I guess you could argue their case if it was being used for something totally different, but all it's wanted for is to keep the project going. I'm pretty convinced that if I'm right, and the actors don't have a legal leg to stand on, that we could convince the others to come to the table and discuss terms for continuing the shoot. The actor who walked out is totally replaceable given that she only shot a couple of takes. I think that this is why she has worked so hard to try and stop us using footage of the other actors too -if she hadn't we would just shrug her off and recast the role.

Can anyone shed any light on this?
Actors certainly have no rights to the footage itself, without other agreement, that would belong to the cameraman shooting the footage, however, just because they don't have claim to the footage doesn't mean they don't have claim to the contents of the footage.

The writers most likely have copyright for the script content they produced, the director has copyright for the influence of their directing, the actors may have copyright for their likeness and performance.  The makeup artists have copyright for the makeup they do.  Everyone acting in a creative capacity that is copyrightable in your jurisdiction will generally be the owner of that copyright unless otherwise agreed upon.

Thus, the actors have no claim on the footage itself, but they may possibly have a claim on their performance or use of their likeness.  They can't decide what is done with the footage without permission of the cameraman, but they can possibly restrict what can be done with their performances and image.

It really depends on local law and that is going to require a local legal expert that can review the case and any applicable agreements in detail.  The specific details of your situation aren't some simple case that can just be answered on an internet Q/A site, as copyright is a tremendously complex thing on any collaborative project.  

This is also why it is important to do contracts for even relatively basic projects.  You don't want to ever have to rely on a contract, but problems do come up and it is important to be clear on who is responsible for what.