Do you know what the legal basis for this is in the UK? I'm curious and google doesn't seem to be giving me anything useful.
I also don't see how this could practically apply to all intellectual property you create whilst employed otherwise you would be open to being sued for posting on a blog since you are distributing the companies IP (i.e the words you wrote) without the companies permission.
I am not familiar with the UK, but even in the US it varies from state to state.
People who aren't explicitly protected by state law get fired for putting something on the internet that their employer doesn't like. There is an explicit carve out in California law (http://www.leginfo.ca.gov/cgi-bin/displaycode?section=lab&gr...) I don't know if there are any other states that have this carve out, but that section combined with "Section 16600 of the California Business and Professions Code states that "every contract by which anyone is restrained from engaging in a lawful profession, trade, or business of any kind is to that extent void." makes quitting your job, taking your own IP made on your own time, and competing with your employer. A protected activity. in California.
Some will tell you otherwise (Google does this) but I sought out advice from a labor law attorney on the legality of their claim and his opinion was that it was largely unenforceable. You couldn't use proprietary information in your gizmo but you could, for example, write a phone operating system on your own time and equipment, quit Google and start competing with Android and they would have a hard time preventing it. But only in California, the employment agreement would hold up in Boston for example.
The employment contracts will include clauses to that effect. All the company has to do is wait till you do something that appears successful and then jump in. When I worked in the UK all employment contracts I was given also prohibited any work elsewhere without company permission - eg you couldn't also work part time at a local supermarket. That is something I have never seen in California employment contracts.
An example of California law working is that the founders of Hotmail were working for other companies when they wondered why you couldn't access email in a browser. eBay was a similar hobby project.
I also don't see how this could practically apply to all intellectual property you create whilst employed otherwise you would be open to being sued for posting on a blog since you are distributing the companies IP (i.e the words you wrote) without the companies permission.