“I must draw your attention to a serious incident,” writes Callaghan. “When Ruby left for school yesterday it was 2017 but when she returned home in the afternoon she was from 1968.

“I know this to be the case as Ruby informed me that the ‘girls’ in Year 6 would be attending the school library to get their hair and make-up done on Monday afternoon while the ‘boys’ are going to Bunnings. Are you able to search the school buildings for a rip in the space-time continuum? Perhaps a faulty Flux Capacitor hidden away in the girls toilet block?

“I look forward to this being rectified and my daughter and other girls at the school being returned to this this millennium where school activities are not divided sharply along gender lines.”

The letter is, of course, hilarious – but, as the online response has shown, it is also indicative of a much wider problem.

Dad’s hilarious letter to daughter’s school perfectly sums up modern-day sexism