Never been sure if it was Jock or John Tamson (Thomson). There also is a question if he was the Rev. John Thomson from near Edinburgh, or an innkeeper from Montrose. However as you say, We're all Jock Tamson's bairns.
Did anyone have "first footing" ? We always had that when a neighbour would bring something like a piece of coal to represent warmth and prosperity. Then of course there was a "wee deoch an doris" (a drink at the door).