Earlier quoted context omitted.
The very, very first clause: > he causes a computer to perform any function with intent > to secure access to any program or data held in ***any*** > computer
No. That's not sufficient to classify the action as illegal. If you're accessing a public website, but through a wireless router that the owner doesn't want you using without paying for, then the data you're accessing is still data you're authorized to access (it being a public website, after all). To get charged under this law, you would have to be accused of the unauthorized access of something on the router itself…
Here's one BBC article that talks about it: http://news.bbc.co.uk/1/hi/magazine/6960304.stm
> The Communications Act 2003 says a "person who (a) dishonestly obtains an electronic communications service, and (b) does so with intent to avoid payment of a charge applicable to the provision of that service, is guilty of an offence".
Seems pretty clear. A person is paying for hotel access; notices their Apple-device using colleague is not paying; spoofs the user agent; - these seem to cover all the points of dishonesty with the intent to avoid paying for a service.
Even if the hotel is in a country that doesn't have that particular law there is probably some fraud law that covers the actions. (I realise now that I should have mentioned the fraud because that's the more serious offence and it seems some people missed my point).