I’m teaching Robert Westall’s The Machine Gunners at the moment with my Year 8 class. When I started reading the book with the class I was surprised by the reaction that the girls gave the book. Basically, they said that they could never like it because it was a “boy’s book”, full of guns, adventure and action. When I first started teaching twenty years ago, girls didn’t respond like this; there was much less stereotyping about what girls and boys should read then. But if you look now at the books that girls are being directed to read, you see that there’s chronic stereotyping going on. Look at this list issued by Amazon which purports to be a teenage fiction list for girls: the covers are all stereotypically “girly”, pink, princessy and “romance-driven”. Interestingly, the books that are suggested for boys are a bit less stereotyped if you look here. However, there is much boys’ fiction which clearly aims to play to certain stereotypes about boys. Look at this list here.
I don’t think this sort of packaging does anyone any good: it puts boys off what can be good books, and it makes girls feel they have to read books with these sorts of covers. The girls in my class are now really enjoying The Machine Gunners but they’ve had to put aside their prejudices before getting into it.
talesbehindtheclassroomdoor 
I think the depiction of girls in The Machine Gunners is poor. I agree with the girls in your class and think it is a shame that they are so often asked to tolerate this kind of book for the sake of the boys’ enjoyment.
Westall is a wonderful writer who is good at female characterisation — particularly with older women such as Mrs Spalding and Chas’s mother. He is also one of the best writers — in any genre — about the Blitz. I’ve never read such gripping descriptions of bombing raids. Girls should read him too — I don’t think it’s right that they should be “protected” from this kind of visceral writing.