The link is huge and cant figure out how to shorten on here for some reason. If you put Jean Style Trousers into the search box, its the first item at £6. You can pick colour from drop down box as not sure which one you're after and fit is standard.
Went to BHS again to get a few more pairs but they'd only get 1 pair left in his size. Went to Next and compared the BHS ones and they were exactly the same length and slightly skinnier in the leg so got some of those instead.