Probably already known - but update of whats happening in London from the Guardian:
The reaction in London
Tuesday September 11, 2001
• The Foreign office has issued an emergency number - 020 7008 0000 - for anyone worried about relatives in America
• All flights from the UK to America have been cancelled.
• The London Stock Exchange has been evacuated. A spokesman for the LSE said: "In response to events unfolding in the US, the LSE is evacuating Exchange Tower as a precaution. We have contingency arrangements in place which means that we will continue to run the market through to the close."
• Tony Blair has returned to London to chair a meeting of the Cabinet's emergency "Cobra" committee in No 10 this afternoon with foreign Secretary Jack Straw, home secretary David Blunkett and defence secretary Geoff Hoon.
• Alert states for Government buildings, civilian and military, have been raised in the UK. Jack Straw has also announced that: "Alert states for diplomatic posts across the world have been raised to their highest level and we are issuing travel advice to all British citizens abroad to take great care if they are living abroad in sensitive areas, to stay in their compounds, to avoid obvious areas of potential risk and to have great care for their safety."
• Earlier, the FTSE 100 Index was down 219.6 points at 4,814.6. Jeremy Batstone at NatWest Stockbrokers said: "The London market was up around 60 to 70 points before - now look at it."
• Some sections of Canary Wharf evacuated