Seems something of an over-reaction to me...
This from the CAA:
"CAA Issues Restriction of Flying Order
11 September 2001
----
Following the terrorist attacks in the USA, an order prohibiting the flight
of non-essential aircraft within UK airspace was issued by the Civil
Aviation Authority at 1830 hours today. The restriction has been issued at
the request of the Department of Transport, Local Government and the Regions
(DTLR).
The Statutory Instrument, made under the UK Air Navigation Order, prohibits
the flight of all aircraft not operating for public transport or for the
emergency services within UK Airspace for 24 hours, starting at 1900 hours
today.
The order was issued by way of a Notice to Airmen (NOTAM) by the Directorate
of Airspace Policy, CAA, today.
For operational enquiries about this order owners and aircraft operators
should refer to the detailed contact information in the NOTAM."