I forgot to mention, I also explored Jump the Gun -  https://www.jumpthegun.co.uk

They have two versions of a Harrington jacket, one with set in sleeves and the other with raglan sleeves. Via email, the helpful staff pointed me to the raglan version, as they are longer.

I was told via email that size 40 is 23 inches across the chest, and 42 is 24 inches across the chest, and size 42 is 27.5 inches in length. I was close to buying from them, but decided I really need a bit more than 27.5" in length.

No - just regular cotton gaberdine as far as I can recall!