Originally Posted by crablab
I'd be flying at 2400ft
Be prepared for Nats to restrict you to 'not above 2000 ft QNH' to reduce Separation Monitoring Function Alerts, and to mitigate the risk of Resolution Advisorys to aircraft flying at 3000 ft QNH within the Class A TMA above.
Yes, the CAA considers the River Thames in London to be a 'congested area'. And here is a
CAA poster regarding flight over built-up areas.