It seems particularly apt that this year’s Lesbian, Gay, Bisexual and Trans History Month theme is justice.

It seems too easy for us to ignore the needs of minorities when we are not directly touched by them or don’t consciously know someone affected. And often we find it hard to conceptualise how significant a community is or how many people may be affected when we can’t visibly see them around us.

Invisibility of minorities is often perpetuated by data. In many ways this is understandable. It is hard to justify investment in a service for a community or issue that you can’t count, and it makes it even harder to demonstrate impact if you don’t know what you’re baselining the uptake against. It also creates a perpetuating loop of invisibility in research and evidence bases that draw on the routine data collection and the integrated demographics.

For lesbian, gay, bisexual and trans communities this data blind spot has been a persistent problem for many years. The lack of visibility of sexual orientation and gender identity in public health data sets was highlighted in the public health outcomes framework LGBT companion document published in 2013, and reiterated in the PHE gay and bisexual men, and other men who have sex with men, health and wellbeing framework.

The invisibility of sexual orientation in the Census has been an area of heated debate over the last ten years, and the move by the Office for National Statistics to pilot and then roll out sexual orientation demographic data collection across the other population surveys they lead has been a significant step forward.

This week Public Health England has published a report on modelling lesbian, gay and bisexual populations in England. It is a unique piece of work that builds on previous modelling done in the run up to the civil partnership legislation. PHE Rainbow Alliance members were involved in the steering group for this work.

The modelling used for this report focuses specifically on sexual orientation identity and drew on the approaches and findings from a range of different national surveys that considered sexual orientation to reach its conclusion, supported by an expert advisory group.

The final analysis included 15 surveys that represent the general adult population of England. The weighted estimate of people identifying as LGB or ‘other’ is 2.50%. If this proportion were applied to the census-based mid-2014 population estimate, this suggests that there would be 1,358,848 people identifying as LGB or ‘other’ in England.

If people who responded ‘prefer not to say’, ‘don’t know’ or gave no answer are assumed to all be LGB, then the upper limit becomes 5.89%.

The report also found the proportion of self-identified LGB is highest in men, younger age groups and mixed/multiple or other (non-White/Black/Asian) ethnic groups. Regionally, the highest prevalence was found in London, North West and North East regions with each having an overall LGB prevalence of 4.26%, 2.51% and 2.27% respectively. There are higher proportions in large cities like London (5.1%), Manchester (3.6%) and Brighton and Hove (9.9%).

The report was developed to provide a population dominator for organisations that have an interest in monitoring outcomes for LGB populations. It is specifically focused on the LGB population and further work is needed to include transgender and intersex people.

This is the first to systematically review existing sources and synthesize data into a new robust estimate of the size of the LGB population of England. These results should be interpreted with caution however. Not only is the result sensitive to error in each survey, but 2.50% is likely to be an underestimate as it is derived from general social surveys that did not have the specific aim of counting the LGB population. The upper limit of 5.89%, on the other hand, is almost certainly an overestimate of the included sources as it is unlikely that all non-responders are LGB.

This work sits alongside work being led by NHS England to improve data collection on sexual orientation in health and social care settings and the continued action led by Stonewall to improve data collection in workplaces.

The PHE report is an important step forward in recognising the size of the lesbian, gay and bisexual populations and for their health outcomes and I hope it will be built upon in the future so that our communities, alongside faith, ethnicity and disabled communities are always counted and continue to count.