“Am I right,” the caller demanded, “in thinking this policy means an eight-year-old girl could now be confronted by a person with a penis in a public shower?”

Apologies, reader, if this fails the "cornflakes test", but that clearly wasn't a concern for the person who rang me to complain about trans women having the right to use the Ladies' Pond on Hampstead Heath.

It may be a surprise to learn that I am not responsible for the City of London's interpretation of the Equality Act 2010. I am, however, happy to defend it.

First of all, call me old-fashioned but I don't think anyone should be "confronting" a child while showering, whatever genitals they have.

This policy simply means trans people will no longer be forced into humiliating or dangerous situations just because they want to go swimming on the Heath.

That means giving them the right to access changing facilities that are appropriate to their gender - something cisgender (non-trans) people take for granted and have probably never even thought about.

Just like cisgender women, trans women are regularly attacked, abused and killed by men. Allowing them a safe space is not rolling back the rights of their sisters: it is a recognition that they were wrongly excluded in the first place.

Unlike men, trans women do not enjoy male privilege - so the idea that they are a threat to women and children is, I think, equivalent to the idea that cisgender women are a threat to women and children. Some women, whether cisgender or transgender, may be potential sex offenders. But we would not exclude cisgender women from changing with children on this basis.

Denying rights to one of the most marginalised groups in society is not a safeguarding measure: it is abuse. What's more, it sends a very backwards message to our hypothetical eight-year-old girl - who may, after all, one day discover that she too is trans.