I can still vividly remember the first session of my first day’s training as a special constable with Thames Valley Police.

The sergeant that was our trainer didn’t cover any points of law, didn’t teach us how to wear our uniform, use our radio, caution a suspect, nor how to arrest and handcuff them. He took us painstakingly through the 1999 MacPherson Report that followed the murder in 1993 of Stephen Lawrence. It was clear how seriously the police took the findings and we were left in absolutely no doubt about are responsibilities as warranted officers. The police won’t claim perfection in 2018, but I was heartened at the time by the seriousness with which the officers I worked with took the report and its huge challenges.

Memories of that training session returned recently, as the 50th anniversary of the murder of Martin Luther King Jr had prompted me to read up on race and racism, something I am embarrassed to say I know in insufficient detail. I came across a research paper, A quantitative longitudinal analysis of exclusions from English secondary schools, that makes important reading for headteachers.

You will see from the quote below that the authors, Steve Strand and John Fletcher, are measured with their findings and quick to point out when smaller data sets make firm conclusions impossible. I anticipated, and knew about, the gross overrepresentation of children with special educational needs and disabilities; I also knew that there was a differential when looking at ethnicity and rates of exclusion, but the detail horrified me.

Strand and Fletcher note: “Although too much should not be made of the ratios for the Chinese and travellers of Irish heritage groups as they are based on small numbers, the numbers of permanent exclusions relative to the number of FTEs [fixed-term exclusions] for Bangladeshi, Caribbean and Other Black children are based on large numbers and are markedly higher than those for White British students. The figures in Table 9 suggest, but do not conclusively demonstrate, that students with different characteristics have different experiences of exclusion prior to a permanent exclusion.”

Furthermore, “too much should not be read into figures for individual ethnic groups, particularly as the whole table is based on data for slightly less than 4,000 permanent exclusions, but there are wide ranges in the numbers and durations of FTEs preceding a permanent exclusion. Nearly every ethnic minority group reaches a permanent exclusion on average after fewer FTEs than White British students and all but the Irish students reach a permanent exclusion having experienced FTEs of longer average duration than the White British students. These data are consistent with a degree of systemic discrimination.”

I think every school leader who holds the power to exclude children should read this paper and pledge to look in detail at what their school’s information might suggest.

Individually, we can all say that we are without prejudice, but Strand and Fletcher suggest that, between us, things could be, and should be, different.

Jarlath O’Brien works in special education in London. His book, Better Behaviour: a guide for teachers, is out now, published by Sage