Within a service area's amenity building, usually public wifi is provided under the operator's name. However, McDonald's always make their wifi available too, sometimes under O2's name.
Roadchef were the first to make their wi-fi free to all customers, but initially (in 2003) it was only made available to customers who purchased from Costa Coffee.
This is a portal page, which tries to provide comprehensive information on a generic subject people are likely to be asking about. If you can add any more information,!