You asked

Please provide the number of visitors to the London region. I would like this broken down by the number of nights those visitors spent, their country of origin and the purpose of their visit for each month over the past six years.

We said

Thank you for your email requesting data pertaining to overseas travel and tourism.

Unfortunately, the tabulations you requested (with monthly breakdowns) are not available, and it would require bespoke analysis in order to create the tables to answer your request. Under Freedom of Information Act 2000 (FOIA), this request is therefore categorised as information not held. As we are not obliged to create information under FOIA, such analysis would fall outside the FOI regime and would be subject to legal frameworks, disclosure control, resources, and agreement of costs. There is more information on our publication scheme on the ONS website: https://www.ons.gov.uk/aboutus/whatwedo/statistics/publicationscheme

You may be interested to know that estimates of overseas visits to London by year and quarter are published on the ONS website. The links are given below.

The most recent annual data on visits to the UK can be accessed via this link:
https://www.ons.gov.uk/peoplepopulationandcommunity/leisureandtourism/datasets/overseasresidentsvisitstotheuk
The following tables may be of interest:
Table 4.13: Includes visits to London by purpose of visit and world region of residence.
Table 4.14: Includes visits to London by nights and spending by world region of residence.
Table 4.15: Includes visits to London by age group.

The most recent quarterly data on visits to the UK can be accessed via this link:
https://www.ons.gov.uk/peoplepopulationandcommunity/leisureandtourism/datasets/overseastravelandtourism
The following tables may be of interest:
Table 12: Includes visits to London by world region of residence.
Table 13: Includes spending on visits to London by world region of residence.

Further enquiries can be made to the customer services team of Social Surveys Division: ocialsurveys@ons.gov.uk. Please don't hesitate to contact the team if you want to discuss commissioning them to produce the data you have requested. They can let you know any costs that would be chargeable.