Background info - DS hates PE, and will do anything to avoid it.
DS's school requires a special track suit for PE (navy with yellow piping down trousers, school name embroidered on back of trakky top). These can't be bought from a shop, have to be ordered by PE teacher - and they are quite expensive.
In the last PE lesson before summer hols, DS fell over and ripped his trakky bottoms. Before this term started I bought a pair of navy joggers as a temporary measure. I told DS to ask the PE teacher what I need to do to order new ones - I double checked, there is nothing on the website or in any of the paperwork to order them.
I got no reply from DS re ordering new ones, but last week - 3 weeks in to term - PE teacher decided DS couldn't wear his temporary ones, and had to wear a pair of trousers out of the 'spares' box, and I need to write a note into school to ask him to order a new pair.
Now, DS didn't really like this, cos the spares don't seem to get washed. I have to say that I'm not chuffed about my darling boy 
wearing a pair of trakky bottoms covered in someone else's sweat after a triple-period PE lesson.
Today I emailed PE teacher (names changed to protect the innocent)
"Dear Mr Farnsbarns,
Sonny needs new track suit trousers as his were badly torn at the end of last term.
I did tell him to ask you how we can get some new ones in the first week of term, but he hasn?t come back to me with an answer. I have provided him with navy joggers to wear pro-tem, but he tells me these are not acceptable, I?m sorry, I did what I thought best in the circumstances.
Can you let me know how we can get the proper equipment please ? Sonny was unhappy about wearing ?spare? trousers last week, as he believed they had been worn by someone else, and not washed. I have no idea whether this was the case or not, but if he needs to wear ?spare? trousers until we can get new ones for him, could we borrow them so that I can wash them for him? I?m sure we don?t want to give Sonny any more reasons to be unhappy about PE lessons !!
Please let me know what we need to do ASAP
Thanks "
Reply came back
"Hi Mrs Bloggins,
I will order some trousers but it will take a few days.
We have many spares which are regularly used by pupils when they are caught short of kit and most of it is pretty clean so it is not usually a problem. Sonny did not respond well to wearing them and I felt at the time it was as he was trying to delay the lesson. He initially said trousers were too short, then said they were too long and then said he did not like the feel of them! After an exchange of words he wore them and got on with the lesson. I did not want to mention it to you as he turned it around during the session and seemed to enjoy himself. At the end of the session Sonny approached me and apologized for his behavior and said he enjoyed the session. I was very happy with this and hoped it would be a start of things to come. I believe it will only take a few good sessions with Sonny letting his hair down and getting stuck in, to change his outlook on P.E., he may find he can perform a lot better than he thinks and have fun."
Now, I have no problem with the idea that DS MUST do PE - and indeed must do anything reasonably requested by a teacher. I am also hopeful (tho sceptical) that we can change DS's attitude to PE.
But the phrase
"We have many spares which are regularly used by pupils when they are caught short of kit and most of it is pretty clean so it is not usually a problem." bothers me a bit. I wouldn't want to wear a track-suit worn by someone else and described as "pretty clean" - yuk!!
So, would it be unreasonable of me to ask if DS can bring a spare pair of trousers home tomorrow night so I can wash them before his lesson on Thursday (I'll wash them again afterwards), or to ask if he can wear his temporary joggers ?? or should I just shut-up and leave it to school ??