The story
From Chelsea, a wealthy area of London in which this type of vehicle is popular, and tractor, an ironic allusion to a large, off-road vehicle, as a humorous juxtaposition between the vehicle's size and power and its use on low-speed roads in a city environment. Potentially also an allusion to their reputation for causing unnecessary traffic congestion, due to their unsuitability for small roads, in a similar fashion to tailbacks caused by tractors on rural roads.
First known use, by meaning
- from 20th c. An SUV or 4x4 vehicle which is chiefly driven on urban or suburban roads for light duties, such as taking children to school.
Etymology from Wiktionary, CC BY-SA 4.0.