He’ll grow out of it,’ my friends told me.

‘He’s so intelligent,’ my family said.

‘Your parents are mathematicians,’ people reminded me. ‘What did you expect?’

What did I expect? We expect many things of our children. Most of the time we are only aware of these expectations when something happens to make it impossible for them to be fulfilled.

When Ben is a baby, Rachel puts his behavioural quirks down to eccentricity. He likes to count letterboxes; he hates to get his hands dirty; loud noises make him anxious.

But as Ben grows and his quirks become more pronounced, it becomes clear there is something else going on. When he is diagnosed with autism, Rachel must reconsider everything she thought she knew about parenting, about Ben, and about how best to mother him.

Reaching One Thousand charts her quest to understand autism and to build a new kind of relationship with her son.

Exquisitely written, this is a thought-provoking reflection on family and understanding and a tender love letter from a mother to her son.