No jeans! We will be running and got sports shirts. But hey, proper protocol requires "business slacks". This in turn rules out sneakers...

It's absurd! All this power gets to some Thais' heads...

English Camp , Thai Camp & all others,

Surely= High heels, Lipstick, eye shadow, limp wrist etc. etc.

OP, you're supposed to take a small bag with you which should contain adequate outfits for every occasion in the camp...

No jeans is a common requirement when a certain level of politeness is required, nothing unusual.

Can you wear a Scottish Kilt?

What on earth is an English camp....?

a gay man from england

Ask Charles Hawtry....

I sometimes teach in a t-shirt, joggy pants and sport shoes when I please.

Most school are pretty strict on dress codes but for summer camps they tend to relax a bit. Jeans are typically a no no though but most get away with black jeans. I think that your school is making an issue because of something in the past. Someone probably abused the leniency and now others have to suffer.

I would just dress professionally but as comfortable as you can. I personally would never wear jeans especially when it is so hot. I find them very uncomfortable compared to dockers or linen slacks.