if its anything like Sophos it will pick up most keyloggers including ones aimed at business's and alert the user.Computer Misuse Act 1990 said:Unauthorised access to computer material
(1) A person is guilty of an offence if—
(a) he causes a computer to perform any function with intent to secure access to any program or data held in any computer;
(b) the access he intends to secure is unauthorised; and
(c) he knows at the time when he causes the computer to perform the function that that is the case.
.Subverting the system is not the answer to his question or the underlying problem though.
And in most eyes it would be an admission of guilt.

But the company has authorised Owen to install the keylogger to the companies computers.
The company own the computer not the indivdual using it so that would throw the computer misuse act out of the window

hmmm, i'm not saying you're wrong, I dont know the letter of the law, but i'd be surprised if there wasn't some requirement for at least an implicit agreement to a laid out policy by nature of using the computers (obviously such an agreement would have to be available to users). I know it is a murky legal area but I can't imagine all the authorisation is placed on the owner of the equipment, imagine if a net cafe owner had keylogging software installed, would that be legal? It's not really a different situation

I'm not sure whether they're paying you or you're paying them makes a great deal of difference, in both cases you'd have to agree to a usage policy.hehe tbh mate i dont even know if im right
With the internet cafe example though your paying them for a private personal use of the internet/email. With a company computer network it is the company that is paying you to use their system for work use.
As you said its all a bit murky area to deal with. It really all depends on what it says in your terms and conditions with regards to usage of the computer system. Some companies i know state that you are 100% NOT allowed to use the PC's for personal use at all. This includes internet. In which case including a keylogging software shouldnt really be a concern.
I'm not sure whether they're paying you or you're paying them makes a great deal of difference, in both cases you'd have to agree to a usage policy.

Even where no personal use is allowed it's a bad security practice to have everyones passwords etc logged, and there's plenty of sensitive data floats around companies that should probably only be viewable by the relevant people, not whoever is lumbered with monitoring keylogs