An undercover police officer used his fake identity to deceive a woman into a 19-year relationship in which they became partners and had a child together, the Guardian can reveal.

The officer concealed his real identity from the woman for the duration of that period, never telling her his real occupation, and using his fictitious identity on the birth certificate of their son.

In 2020, after the couple were engaged to be married, the woman discovered that her fiance, whom she believed to be a businessman, was in fact a police officer who had subjected her to a sophisticated deception lasting almost two decades.