MeshHopper is the company behind the paid-for Thames Online Wi-Fi network, which went fully commercial last year and which covers the same stretch of the river, from Millbank in central London to Greenwich in south-east London.

The free network, which has been branded as "online-4-free.com", gives users free access if they agree to view a 15 to 30 second advert every 15 minutes. If users don't want to view the adverts, they are charged one of a range of tariffs, including £2.95 per hour or £9.95 a month.

The free service operates with modest download speeds of 256Kbps. The paid-for services operate at a faster 500Kbps.