I envy you guys with your cold winters. I adore the look of a nice flannel suit. It's probably one of the grass is greener scenarios. I'm sure some would like to have the ability to wear summer suits year round and only require half as many clothes. A four season suit here is a lightweight hopsack or wool/linen blend.
Autumn/winter are my favourite seasons, I love the cold weather (not to be confused with bad weather). I like a nice sunny day with the temperature being around or below 0c, the air is nice and fresh, and I'm all comfortable in my thick suit, overcoat, leather gloves, and dress boots. I too love the look of flannel suits, as well as soft tweed, and apparently corduroy based on that three-piece Hudson fit.
I am a fan of early spring, but I don't really like summer much, or summer suits. Linen just isn't my thing. I actually returned my linen Hudson for a wool-silk-linen Lazio because I wouldn't get much use out of it in the UK, there were like 2-3 days this summer where a pure linen suit might've been a good option, but lightweight wool was perfectly fine for this too (It's easy to layer up lightweight wool for wearing in winter).
I'm not sure what happend last winter in London, it did not get nearly as cold as I'd wanted, and so I only wore an overcoat like 4-5 times. It's pretty cold so far this year, so I decided to get the navy DB overcoat since it seems to be getting colder.