Chiltern Edge High School in England introduced new uniforms at the beginning of the academic year and the only leg wear permitted are trousers or skirts.
One parent of a pupil at the Oxfordshire school asked staff if his son could wear tailored shorts but the soon-to-be academy said that they were not part of the uniform.
However, when quizzed about the boy being able to wear a skirt, the bemused father said he was told that the uniform policy was gender neutral and boys could of course wear a skirt.
The case came to light at the weekend and comes as temperatures are expected to be as high as 26 degrees in the area next week.
The school, in Sonning Common, introduced the new uniform in September last year. In August the school will join the Maiden Erlegh Trust and become an academy - an independent, state-funded institution which receives funding from Westminster rather than the local authority.
The school has the capacity for 900 pupils, but as of January last year the student base was only 507.
Alastair Vince-Porteous, a parent, said: “I know that in the past other schools have worn skirts so I asked if my son able to do that and the school said yes.
“I was told shorts are not part of the uniform.
“It’s a shame we can’t be more grown up about it, we aren’t asking for rara skirts or skinny jeans, just grey tailored shorts for two months a year, it’s not a big deal.”
Another parent said: “We send our children to Chiltern Edge, not Eton!”
Joanne Muday said: “It’s nuts to make the kids wear blazers and ties when it gets very hot.
“If people say the kids need to stick to the rules, we change the rules!”
Students hail from nearby areas such as Caversham, Reading, Henley-on-Thames, and Prime Minister Theresa May’s constituency of Maidenhead as well as Sonning proper, where the PM lives with husband Philip.
The school’s headmaster, Moira Green, said: “In September 2017, with the support of parents, Chiltern Edge made the decision to move to a more formal uniform. This has been a success.
“Maiden Erlegh Trust, in preparation for September 2018, wholeheartedly support Chiltern Edge’s adoption of a more formal uniform.”