Report
Illegal online gambling: Challenges of estimating the size of the illegal gambling market
The final chapter of the Gambling Commission's research into the illegal online market, focusing on challenges estimating the size of the market.
Annex A - Summary of next steps to improve estimates
The following section outlines key information gaps and their impact on the reliability of estimates. Options for new sources of data and evidence are set out, alongside an assessment of the feasibility of the extent these options will satisfactorily fill these information gaps.
Options for improving ‘dwell-time‘ approach
More reliable estimates of gambling activities participated in on illegal websites
Effect on reliability: Medium.
New data source: Consumer research and surveys.
Consideration: Data from consumers who have used illegal websites can help us understand how activities participated in differ from behaviour in the legal market. Current data is based on Consumer Voice survey with relatively small sample size.
Feasibility: Medium - We will be asking this question in further stages of Consumer Voice research. This is unlikely to provide very large sample sizes -as recruiting consumers who are aware they have used illegal websites is challenging. But it will help strengthen existing survey data.
Data to allow betting expenditure to be included in the dwell-time approach
Effect on reliability: High.
New data source: Operators.
Consideration: Betting expenditure is less correlated with time on site and/or session length compared to slots or casino products. Data from regulated operators would help us to create a better proxy to improve ability to create a reliable estimate.
Feasibility: High - We expect that operators will be able to provide data that will help improve these estimates. This would only be needed from a sample of operators to improve assumptions that can be made with the data. Other challenges, however, need consideration – such as the extent this data is likely to reflect consumer behaviour in the illegal market. This is discussed later in this section.
Updating ‘Patterns of Play’ with more current data
Effect on reliability: High.
New data source: Operators.
Consideration: As Patterns of Play is several years old, current operator data could be used to verify and update estimates of expenditure per minute by product and explore if trends seen in market Insight data for slots are also seen in other gambling products.
Feasibility: High - As stated previously, operators are likely to be able to help us bring spend per minute calculations up to date. This would only require input from a sample of operators to update these assumptions.
Understanding of proportion of website visit time spent gambling – and how this varies between legal and illegal environments
Effect on reliability: Medium.
New data source: Consumer research and surveys.
Consideration: Understanding differences in latent time between illegal and legal environments will help us improve reliability of estimates.
Feasibility: Medium - We know that many consumers that use illegal sites are not aware if they are regulated or not. Therefore, ability to accurately report differences in behaviour might be limited. The more consumers report gambling experiences to be similar in both environments, however, would increase confidence that behaviour in legal environments could be generalised to illegal.
Options for improving ‘dwell-time‘ approach
Improving estimates of engagement with legal websites and Apps
Effect on reliability: High.
New data source: Operators.
Consideration: SimilarWeb estimates are associated with margins for error. Operators can help us verify the reliability of these estimates by sharing data on known consumer engagement with licensed websites and Apps.
Feasibility: High - We expect operators will be able to provide data that will help us verify reliability of Similarweb estimates by comparing these results with their own data on engagement with their platforms.
Options relevant to both approaches
Improved understanding of how expenditure differs between illegal and legal environments
Effect on reliability: High.
New data source: Consumer research and surveys.
Consideration: We know that consumers have different motivations which lead them to use illegal websites. We need to know more about how consumer expenditure varies between these environments – and for different groups of consumers.
Feasibility: Low - This is likely to be the greatest challenge. Consumers generally do not have good recall of gambling expenditure – and often do not understand if they were gambling in legal or illegal environments. Qualitative research will help us better understand how experiences differ – but it is unlikely we will be able to obtain robust data to draw strong conclusions on expenditure differences in each context.
Improving estimate of Virtual Private Network (VPN) use
Effect on reliability: High.
New data source: Consumer research and surveys. Exploring trends in VPN downloads and subscription fees in open banking data.
Consideration: Visits to illegal websites will be hidden by use of VPNs. We have seen a change in the amount of VPN downloads in recent months. We need to better understand the impact of this on the data we have collected. Our existing survey data is based on small samples sizes.
Feasibility: Medium - Additional survey data on this topic will be provided by Gambling Survey for Great Britain (GSGB) later this year. This will provide a larger sample size to improve our estimates.
Search terms used to identify illegal websites
Effect on reliability: High.
New data source: Consumer research and surveys.
Consideration: We need to maintain understanding of consumer motivations for using illegal sites so we can update and improve the list of search terms we use to identify illegal websites.
Feasibility: High - On-going consumer resaearch – such as Consumer Voice – will allow us to maintain up to date search terms reflecting current consumer behaviour. Regular reviews will be used to ensure insights from the research are shared and applied to our list of search terms.
Annex B – Exploring motivations for accessing illegal gambling through estimates of search term volumes - Supplementary data
Last updated: 6 November 2025
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