UK outbound business trips 2011-2021

Data based on the International Passenger Survey (IPS), which covers all major air, sea, and tunnel ports. These results do not include any travel via the Channel Tunnel vehicle trains as the trains were isolated and no interviewing could take place.

Additional note from the source:
"Estimates produced from the IPS are subject to sampling errors that result because not every traveller to or from the UK is interviewed on the survey.
Sampling errors are determined both by the sample design and by the sample size - generally speaking, the larger the sample supporting a particular estimate, the proportionately smaller is its sampling error. The survey sample size in 2021 is much smaller than in previous years because of the travel restrictions resulting from the coronavirus (COVID-19) pandemic.
The estimates presented in this article for the whole of 2020 must be treated with particular caution, since the methods used have not been fully scrutinised or tested.
The estimates presented (...) make the best use of the available data and methods to produce estimates of international visits and spending. However, as noted, the numbers are small and the results should be treated with caution."