The saying
One for the Road originates from the 12th
Century.
At one end of
London's
Oxford Street lies
Marble Arch. From the 12th Century up until
1783, the
Tyburn Gallows stood there, being a place where petty thieves,
political prisoners and
notorious criminals were hanged. One the way to the
hanging, they were lead down the road which is now
Oxford Street, but before they left they were allowed one last drink, which is where the saying comes from. In fact,
Oxford Street's only
pub,
The Tottenham, is down the other end of the street, at the
Tottenham Court Road end.
Once the criminal had drunk their last
drink, they were lead towards the
gallows on a wagon, which is where the saying
on the wagon comes from - i.e. they weren't allowed to drink any more.