lead pipe cinch

Factual Questions
1

Anyone know the origin of either ‘lead pipe cinch’ or
‘johns your uncle’. Have a friend who’s never heard either of these and wants to know what they derive from???

thanks

2

I think the actual phrase is “Bob’s your uncle.” And it originated in the 1880’s Britain. See worldwidewords

3

Dave Wilton’s site explains it as a bit “uncertain.” But from the late 1800’s. He gives a few possiblities.