Hi there, My thoughts on the 'alley O' was that ships where built 'at the bottom of the streets near the docks' and when you looked down the street it resembled an alley! areas in the UK that spring to mind are. Liverpool, Sunderland, Newcastle, Glasgow, etc. etc. So 'the big ships sailed down the alley alley O' was probably made by kids somewhere in these regions? Just a slightly educated guess but as valid as any I think!

Peace and Love Joe.