Bought either ready made or cut down from trews, these are 'Take Ivy' items at their best. Excellent on these hot days, worn at the correct length, with loafers or Docksides. But, as Moose has observed with reference to the Madras jacket, the accompanying garment must be restrained. A plain white t will do it for most. I like a pale blue Brooks half-sleeve. L.L. Bean do a nice pair. But they won't bleed.
With an untucked white OCBD rolled sleeves for me
untucked with shorts, too... it's not the 50s, right? you wouldn't wear shorts with socks either?
Absolutely. You wouldn't want to look like a 'take ivy'-styled charicature!
Plain white T (always untucked) sounds about the height of it, also OK with a grey sweatshirt.
As anything you would wear above shorts is untucked, they are usually OK with pleats.