Suse, I find that Isla needs a high rise also, I orginally had a standard size int eh WCDN but sold it on as I was having to pin Isla down to get it on her just right. Then I got the Plus & it was much better.
So No I don't think its odd that Euan fits the Plus, I think (personally, this isn't a WC statement LOL) that the standard is better suited to up to 6 months or small bubs. The thing is, the nappy was designed by a Mum with a bub who is a pocket rocket. The WC DD that the nappy was used on is 6 months older then Isla, But Isla is taller & probably weighs more then her. She is a little pixi. Also apparently by some freak occurrence all the testers of the nappy where little also. Which is why the PLUS was introduced.
I bought a standard (bargain on B4B) to add to my Mr Doodle Stash. Not actually for ISla. If I am desperate for a night nappy though, it will fit her. She had it on yesterday & did a crap in it LOL.

As for DH either playing dumb or just being dumb LOL.... I dunno either. Also getting him to show me first wont really help because he doesn't get the doing them either. Its been awhile but he has in the past even put them on backwards which just baffles my mind as how can he look at it & think thats was right? Even back in the sposies age, he never put the on tight enough. I am fussy when it comes to how they are put on. No way in the world would I trust a nappy put on by DH over night, sposie or MCN. I have tried to gently show him the error of his ways but he is so sensitive & easily offended its easier to just do it myself!

eta - I find that the Lotus Night nappies (side snapping) has a nice high rise