British Airways B744 at London on Feb 7th 2014, cabin did not pressurize

A British Airways Boeing 747-400, registration G-CIVI performing flight BA-197 from London Heathrow,EN (UK) to Houston,TX (USA), was climbing out of Heathrow's runway 27L when the crew stopped the climb at FL100 when the cabin did not pressurize. The aircraft dumped fuel and returned to Heathrow for a safe landing on runway 27R about 80 minutes after departure.

The rotation BA-197 and BA-196 was cancelled.

A passenger reported the captain announced there had been a problem with the pressurization system.