However, Leonard Morrison, a marine physics professor who has based his career on believing that the Thames barrier was built in the wrong place, disproves Hopkins' theory with his independent but sophisticated computer model - which predicts that the storm and spring tide would merge to form a 46 metre-high surge.

After a series of mis-informed meetings with Deputy Prime Minister Campbell (who becomes outraged at the inaccurate forecasts) Hopkins feels guilt ridden as valuable time has been wasted.

During a last-minute meeting at COBRA (Cabinet Office Briefing Rooms) in Whitehall, the authorities realise that Central London would be inundated in three hours.

As the COBRA authorities and military forces struggle to evacuate over one million people from the city, Police Commissioner Patricia Nash is designated the emergency coordinator by Campbell and works with the rest of the team, including Major General Ashcroft, transport chief Johnson, and a guilt-stricken Hopkins.

Rob and Sam jump into the Thames to escape the swamped barrier, whilst Leonard is saved by a military helicopter and taken to Whitehall to advise COBRA.

General Ashcroft disagrees and lobbies the Prime Minister to authorise an air strike to destroy the barrier, hoping to create a surge to push the water back out of London.

Miniature sets in water tanks were used to shoot larger flooded buildings such as the Thames Barrier, London Underground and car parks.

[5] It also played as a mini-series in Lithuania, Spain, Italy, the United States (via Ion Television), New Zealand, South Africa, Canada, Finland and Denmark.