Great info. I've actually got two versions of a shirt I love - one in a 15 neck I wear without a tie both with and without a jacket, and on in a 16 I wear with a tie, under a jacket. Should get the latter tailored by I'm too cheap.
I haven't owned denim jeans for 20 years (46 years old now) - just didn't like the feel of them.
But I have informal pants such as chinos and corduroys. Nothing wrong with jeans at the right time though, and I'm probably getting a pair soon.