emmm I haven't heard the original version, but the one sung by traffic is actually about brewing beer. The tune sounds good, and once analyzed for the first time, it sounds like medieval methods of torturing and killing a man.

They hired men with their scythes so sharp
To cut him off at the knee;
They rolled him and tied him around the waist,
And served him barbarously.

They hired men with their sharp pitchforks
To pierce him to the heart,
But the loader did serve him worse than that,
For he bound him to the cart.

John Barleycorn in the traffic song is the personification of barley and the process used to plant, harvest and brew the barley for beer.