Betty Knight was the only black teacher at a predominantly white college in Alton, Hampshire.

She had a good record as a conscientious teacher at Havant and South Downs College, where she helped teenagers who were resitting their GCSE English exams, and was proud that many of her students would go on to university and professional jobs, “knowing that a black teacher helped to get them there”.

So she could not believe the paradox when she was admonished for not doing enough to promote equality and diversity in one of her lessons.

Knight, 54, who was born in Botswana and holds British citizenship, said she was left “stunned and demoralised” when two assessors, who were both white, gave her damning feedback after a 25-minute observation.

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