Sex and the Census: A review of the sex question since 2001


This review looks at how the ‘sex’ question has been interpreted in the Censuses for Scotland and for England and Wales since 2001, and plans for England and Wales in 2021.

The analysis shows differing interpretations of the sex question, and a lack of readily accessible guidance. The examples below suggest it is not entirely clear whether in recent years the Census has collected data on biological sex (as recorded at birth), legal sex (which would reflect any change made through the acquisition of a Gender Recognition Certificate post-2004) or gender identity. Correspondence from the National Records of Scotland (NRS) has stated: ‘the census has never defined what we are measuring in relation to sex in previous censuses’ (5 December 2018).

For the purposes of the Census (Amendment) (Scotland) Bill, which is currently passing through the Scottish Parliament, we would suggest the Lead Committee (Culture, Tourism, Europe and External Affairs Committee) (CTEEA) seek further clarification on what was done in Scotland in 2001 and 2011, including copies of previous guidance for respondents in Scotland and information on how this was disseminated.

Review of the sex question since 2001

In response to a Freedom of Information request, in 2011 the Office for National Statistics (ONS) stated (emphasis added):

‘Responses to the sex question, which has been asked since the first UK Census in 1801, are used, together with age, as the basic variable, by which the full range of other characteristics, such as health, employment and unemployment in particular occupations and industries, education levels, migration, etc are measured. Such characteristics have always been measured by the sex as reported subjectively by the respondent.’ (Office for National Statistics, 2011)

Census responses have never required corroborating evidence for any variable reported, including sex, meaning that responses on this and all other topics have always been self-reported in a technical sense. However it is less clear that respondents have always been expected or instructed to provide sex “subjectively”, rather than as legally recorded.


Prior to the 2001 Census in England and Wales, the campaign group Press for Change suggested that there was a widespread understanding that, in the absence of any contrary definition being provided, respondents were expected to provide their sex on the basis it was recognised in law:

‘Because UK law does not fully recognise trans people in their true gender[1], the possibility arose that once again, it would be impossible to provide a truthful answer which also matched legal requirements. There is a legal obligation to complete the census form accurately, so trans people faced an unpleasant dilemma.’ [2]

Press for Change went on to highlight that in December 1998, ONS had advised a correspondent that in England and Wales “Should there be the traditional question on the individual’s Sex in the 2001 Census, it would be reasonable for you to respond by ticking either the ’Male’ or ’Female’ box whichever you believe to be correct, irrespective of the details recorded on your birth certificate.”

This appears to have been regarded as new advice: Press for Change noted (their emphasis) that the ONS response “makes it clear that trans people can now give an answer which is both truthful and legal”. It is not clear how far this advice was provided other than on the Press for Change website (link no longer active), as responses to individual enquirers, or shared through one or more campaign groups.

That the advice in 2001 for England and Wales was regarded as new at that point is reflected in oral evidence to the CTTEA Committee (Official Report 6 December 2018 col. 25) from Mr Tim Hopkins (Equality Network):

… [the question in 2011] “in effect, was a self-identified sex question. As the committee has heard, in 2011 the 1 per cent of people who are trans were told to answer it according to the sex that they believed themselves to be. In fact, the Office for National Statistics issued guidance for the England and Wales census for 2001 that said the same thing, so this has been going on for two decades.”

We have not found a record of any discussion of the implications of the passage of the Gender Recognition Act 2004 on the advice issued for 2001, prior to the 2011 Census.

2011 Scotland census

The Scottish Government Policy Memorandum on the current Census (Amendment) (Scotland) Bill states that the 2011 Scotland Census collected data on ‘self-identified sex’, which effectively conflates sex with gender-identity:

‘The 2011 Census recognised that society‘s understanding of sex has changed and guidance provided explained that the question was being asked in terms of self-identified sex.’ (Scottish Government, 2018)

This guidance is detailed in NRS correspondence to the CTEEA Committee (see below)  which states the guidance was not published on the Census questionnaire, although it was made available online.

At the time of writing we have however, been unable to locate an online record [note: this has since been provided by NRS and can be accessed here]. It is not clear how this was disseminated and therefore how respondents were made aware of it. NRS state:

‘The 2011 Census sex question asked “What is your sex?” with two response options but it did not specify any more details in the question text. The additional guidance provided online for this question in 2011 was:

I am transgender or transsexual. Which option should I select? If you are transgender or transsexual, please select the option for the sex that you identify yourself as. You can select either ‘male’ or ‘female’, whichever you believe is correct, irrespective of the details recorded on your birth certificate. You do not need to have a Gender Recognition Certificate. If you are answering for someone who is transgender or transsexual then where possible you should ask them how they want to be identified. If they are away, you should select the sex you think they would wish to be identified as. You can select either ‘male’ or ‘female’, irrespective of the details recorded on their birth certificate. You do not need to know if they have a Gender Recognition Certificate.”

It should be stressed that this detailed guidance was only published online and was not part of the instructions on the form. The question ‘What is your sex’ did not provide any specific definition of what was being measured within the question text itself. There was no opposition in 2011 to the self-identified nature of this question but this may well reflect that fact that many people were not aware of the more detailed guidance. The starting point for 2021 has been that this question will continue to be self-identified.’ (National Records for Scotland, 5 December 2018)

Written evidence submitted to the CTEEA Committee by the Equality Network and Scottish Trans Alliance refers to the above guidance and suggests that the 2011 Scotland Census collected self-identified sex, irrespective of whether a person had a GRC:

‘Guidance for the sex question on the 2011 Census from National Records Scotland made it clear that trans people should answer with their self-identified sex (also known as their gender, or gender identity)…

This means that trans women were able to select “female”, and trans men were able to select “male”, regardless of whether or not they had received a Gender Recognition Certificate.’  (Equality Network and Scottish Trans Alliance, 2018)

In 2014, an ONS report for England and Wales on the 2011 Census Variable and Classification Information stated that the ‘sex’ question refers to the ‘the classification of a person as either male or female’. The reason for asking the question is cited as follows:

‘This important information is required to produce statistical breakdowns of the population by sex. It is also used for equality monitoring.’ (Office for National Statistics, 2014)

This explanation suggests that the sex question refers either to biological or legal sex. Sex is a protected characteristic under the Equality Act 2010, which some argue should be interpreted as biological sex (see Freedman, 2018) and some as legal sex, that is post-GRC (see Cowan 2018). On either understanding, public authorities appear to require data on sex as officially recorded on an original or revised birth certificate to meet their statutory duties under the Act.

In a subsequent topic report on Gender Identity (2016) ONS suggested that the sex question remained unclear, and the instructions should be reviewed:

‘Discussions highlighted the need to clarify what information is actually being collected when we are asking about sex and what data are actually required. For example, someone born male but living as female may not have legally changed their gender but would still identify as “female”. It was noted that numbers would be small, and some participants considered whether information on sex could be replaced with asking about gender. In addition, there were discussions around biological sex and the requirement for data on sex to calculate fertility and mortality statistics and meet health needs (for example, cervical screening for trans men). There were also considerations about how sex and gender may relate to inequality. It was noted that “sex” is also a protected characteristic, so important for equalities monitoring. As such, there was a requirement to take this into account when considering any changes to the information on sex already collected…

In light of the issues raised in terms of gender identity, there is a need for us to review the instructions around the sex question, particularly where the sex question is asked without a gender question.’ (Office for National Statistics, 2016)

England and Wales 2021 census

More recently, the UK Government White Paper on the 2021 Census has confirmed that sex will remain as a compulsory question in the next census and retain the existing binary male/female responses (it will also explain that a gender question will follow later). The Equality Impact Assessment explains the importance of mirroring the Equality Act 2010, in relation to the protected characteristic of sex:

‘Maintaining the current question is important to preserve continuity of data in respect of the protected characteristic of sex. The question on sex (male or female) is established in the census, and it is essential to the evaluation of inequality related to that protected characteristic. Consideration has been given to amending the question to reflect a wider range of options, given that there is greater recognition than previously of individuals who reject the traditional “binary” view of sex. Nevertheless, the protected characteristic of sex as defined in the Equality Act 2010, and as relevant for the PSED, is whether a person is a man or a woman. This binary concept of sex is, in turn, fundamental to the Equality Act 2010 definition of sexual orientation and of gender re-assignment, and to the law on marriage and civil partnership and many other matters.’ (Office for National Statistics, 2018)

[1] The Gender Recognition Act 2004 was the first time people were provided with a method of changing their legal sex under UK law.

[2] Comment on Press for Change website dated February 1999, recorded in Annex A of Equality Impact Assessment Screening 2011 Census (Diversity Solutions, 2008: 8)