Britain's Civil Aviation Authority (CAA) produces a wealth of useful statistics relating to aviation in the UK on a monthly basis, looking at the activities of both airlines and airports.
The annual summaries of these statistics are fascinating and provide some real insights for travel managers.
One of the datasets the CAA produces looks at statistics on every route from British airports. In this week's chart, we look at the top twenty routes from London airports, which are shown below.
The top 20 is fascinating in itself but it is the change in the top 20 in the past decade that is more revealing.

Source: CAA. Note: All routes are from Heathrow except for the two marked with *
Heathrow to JFK keeps its top spot but perhaps not for long. The current number two route – Heathrow to Dubai – was only the 10th busiest route 10 years ago and is a stark portrayal of Emirates' growth strategy. At this rate, JFK is soon likely to be toppled, although if New York's Newark is added on then New York's prime position may remain for a little longer.
The slump of Heathrow to Paris – from fourth position in 2004 to 10th in 2014 – does not mean that Anglo-French business relations are getting worse. The reason is that a substantial chunk of air traffic between the British and French capitals has shifted onto Eurostar.
Another point worthy of note is the growing importance of India. Mumbai and Delhi are now at 15th and 18th positions in the ranking, up from 73rd and 134th a decade ago.