Cars, SUVs, vans and motorhomes all need TV licences if gadgets used to watch telly are used in them. That's according to correspondence I've received from the Department of Communications. Even a tent needs one if you catch Seoige and Seoige on a Sinclair.
The Department also said that any premises using a laptop or home PC to catch a TV signal needs a licence. That is, unless it's accessing the signal online, in which case it's exempt.
Mobiles are exempt.
But using a Slingboxes would mean that any device that connects remotely to it will draw down a need for the host premises to have a TV licence. Wonder what happens if you use it on the bus, though?