Would a portable AC be basically pointless in a draughty Victorian house share?

Our house has been absolutely stinking hot, so I’ve been looking into getting a portable AC unit for my bedroom/office.

I’ve now come across this New Scientist piece [link] and I’m trying to work out whether I’ve understood it properly, because it sounds a bit mad.

Most portable units sold here have one hose. They cool the room, but also use air from the room to cool the hot part of the machine, then chuck that air out of the window.

That air has to be replaced, so warm air gets pulled back into the house through gaps around doors, windows, floorboards, etc.

Which makes me wonder: in an old, draughty Victorian house share, would it just spend the whole time pulling hot air back in and fighting itself?

Apparently a second intake hose solves most of the problem, but hardly any units sold in the UK seem to have one.

Has anyone here used one in an older house or flat? Did it actually make a decent difference, or was it a bit crap?