The phrase 'the reason why', as pointed out, has a long history but is it correct? I would say "the reason that I am late..." or "the reason for my lateness..."
"The cancellation of the train is the reason that I am late."
But I accept that 'the reason why' is a hardy indefensible that isn't going away.

Hi Will, I see you got there first. I missed your comment on Durham.

Gayla is, I believe, an earlier pronunciation that lives on in the UK only in the north of England. It is the Durham Miners' Gayla. Elsewhere in the UK gahla prevails.

My apologies, Agustin, for talking rubbish. 'Who' is the subjective form and 'whom' is the objective form. Perhaps you knew that and were simply saying that it's okay to say 'who' informally in the objective form.

Our grandfathers and great grandfathers in Britain used the 'ize' spelling. It's strange that we went over to the Frenchified 'ise'. I hope we return to the correct 'ize' form.

All these 'regards' phrases sound a bit laboured to me, the sorts of phrase people use to give a gloss of officialness. I'd say, 'as to'.

The traditional use of 'first generation' refers to those born in America. Immigrants weren't generated in America. They came here.

For those of my generation (ahem) the plural is nos. either with a capital or without. It's a usage I haven't seen in quite a while.

There is a surprising assertion above from Agustin. "Whom is the formal way of saying who."
'Who ' is the nominative form, 'whom' is the accusative.

I was about to suggest that Americans enjoy the fancy longer word, for example 'burglarize' instead of 'burgle' but then I realised that we Brits say 'acclimatise' and Americans say 'acclimate'. So I won't.
Yes - I do know there is inconsistency in the spelling above between 'realised', 'burglarize' and 'acclimatised' but that is another kettle of Anglo-American fish...