Virgin Media is doubling customer broadband speeds... for free.

Great Britain is leapfrogging ahead in the global broadband speed race with two announcements this morning that represent major advances in British broadband.

First, Virgin Media is announcing it will double the broadband speeds for four million of its customers starting next month, for free.

The company says it will be the first residential provider in the United Kingdom offering 120Mbps broadband — a 20Mbps speed increase for their existing 100Mbps clients.  Customers on Virgin’s 10, 30, and 50Mbps tiers will soon receive free upgrades to 20, 60, and 100Mbps, respectively.  Those on the company’s popular 20Mbps plan will have their speeds tripled to 60Mbps.

That’s a major advancement for British broadband, where dominant BT-provided DSL runs at speeds averaging just over 6Mbps.

The new speeds were made possible by “modest investments” in Virgin’s fiber network, according to Virgin Media CEO Neil Berkett.

Berkett said the new speeds would help meet growing demand for faster access to support the proliferation of new digital devices.  Because Virgin invested primarily in fiber and cable broadband, speed upgrades on their existing infrastructure come “at a fraction of the cost of other network operators.”

That understanding was not lost on Sky Broadband, a growing competitor in the United Kingdom.  Sky this morning announced it has launched a newly-upgraded 100Gbps optical network to support its 3 million broadband customers.  The company is spending several hundred million British pounds on updating its network to position itself to become Britain’s largest Internet Service Provider.

Sky’s new network is based on the latest Alcatel-Lucent fiber technology, capable of supporting 100Gbps speeds on each of the individual 88 wavelengths on a single optical fiber.  Sky deployed the new dense wavelength division multiplexing technology on its existing optical fiber backbone network, demonstrating the infinite upgrade possibilities fiber optic technology offers.

Sky pitches its network capacity to consumers as a key benefit of its service, noting it is free of “traffic management” policies that reduce speeds for customers of other Internet providers.

The upgrade arrives just in time to handle the expected explosion of online traffic with this week’s introduction of Netflix streaming across Great Britain.