In London, during the late 1800's, buses were pulled by horses. Some bus drivers loved their horses so much that on their days off from work, they would ride on their own buses just to make sure that other bus drivers took good care of their horses.
The Online Etymology Dictionary says that it was first recorded in 1768: http://www.etymonline.com/index.php?search=%22pretty+penny%22&searchmode=none
This has a more complete explanation, towards...
'Cheek by Jowl:' means - nery close together, side by side.
It originates from: The Midsummer Night's Dream by Shakespeare - if two people are together with one person's cheek right by another...