I’d been looking at wrong outlet, condensate is plastic and runs across the side of the house internally and exits into the gutter at roof level. It’s a good 21.5mm,god knows why I thought the curved over one was it.
The same gutter I was admiring the icicles on and clearing the icy puddles off the steps directly below the condensate pipe.
No lagging on it but I can sort the inside section. I’ve put a hot water bottle on just in case that helps.
Thanks