The first source is the UK censuses, the main instrument for measuring the stock of residents. In the 2001 Census, approximately 36,500 people born in Portugal were living in the United Kingdom. Ten years later, the 2011 Census recorded about 88,000, indicating substantial growth. The most recent results — 2021 for England, Northern Ireland, and Wales, and 2022 for Scotland — point to around 165,000 Portuguese-born migrants, confirming both the growth and consolidation of the Portuguese resident population in the United Kingdom. These figures refer to individuals born in Portugal, regardless of their current nationality, who were usual residents at the time of the census.

The second source is the EU Settlement Scheme (EUSS) statistics published by the Home Office. These record administrative acts — applications for residence status by European Union nationals. Between 28 August 2018 and 31 March 2025, approximately 312,000 applications by Portuguese nationals for settled status and 177,000 for pre-settled status were concluded. Considering only the grants of settled status, there were on average around 44,500 such grants per year over this seven-year period. However, these data do not directly reflect the number of Portuguese migrants entering or residing in the United Kingdom. EUSS statistics count applications and may include duplications (for example, individuals who moved from pre-settled to settled status), family members of Portuguese nationals without EU citizenship, individuals who no longer reside in the United Kingdom, or citizens who were eligible to apply but never actually settled in the country. The methodological notes provided by the ONS and the Home Office highlight these limitations and emphasize the impossibility of making direct comparisons with census data (read more here).

The third source is the UK National Insurance Number (NINo) registrations. Given the limitations of the EUSS data, the Portuguese Emigration Observatory relies primarily on NINo statistics to measure inflows. Registration for a National Insurance Number is mandatory for anyone wishing to work or access public services in the United Kingdom, thereby providing broad coverage of labour migration. This source has the advantage of recording individuals actually present in the country, avoiding the problems of multiple applications or registrations by non-residents, and thus constitutes a more reliable measure of inflows.

In conclusion, any rigorous analysis of Portuguese emigration to the United Kingdom must distinguish between stock sources, such as the census, which allow for the assessment of the size and distribution of the resident population, and flow sources, such as National Insurance registrations and, to some extent, EUSS statistics. Only a combined and critical reading of these data sources makes it possible to understand the true presence of the Portuguese population in the country, avoiding interpretations that might overestimate or underestimate the migratory phenomenon.

Cite as Vidigal, Inês (2025), “On the data sources for emigration to the United Kingdom”, Observatório da Emigração. http://observatorioemigracao.pt/np4EN/10474.html