My friend says she watches Wimbledon live on her work PC. Is this covered by the TV licence she has for her home TV or do the employers need a TV licence to cover this?
A TV licence does cover live TV reception while 'on the move', so its application isn't restricted solely to the holder's home address. (e.g. if you can get a good enough wi-fi signal on a train to watch live TV, the train doesn't need a licence!)
However if the laptop is plugged into the mains at work then legally it has been 'installed' on those premises and a licence (relating to those premises) is then required.