Again thanks, I'm learning a lot, or perhaps you are reminding me of things I've temporarily forgotten.

Interesting what you say about Papias. There is another version of Matthew, allegedly closer to the Hebrew. I think I have a copy of it somewhere in the loft.

Q is of course still merely hypothetical. I think your intuition about Luke may well be correct. There is certainly (indirect) evidence in the text that he was aware of Matthew. If so, why do we need Q?