i should get out more.... There are many different theories around, but the real answer is that nobody really knows. The word "float" seems to have the meaning "delivery vehicle" only when applied to milk floats and, very occasionally, coal floats. However it seems likely that the latter usage resulted from the use of the word with milk, so it would appear that the origins of this meaning of "float" just aren't known!
Q: Why are they called "Floats"? A: This has to be the most commonly asked question of them all! There has been much discussion on this topic on the mailing lists, I receive a steady stream of e-mails asking this question, and there was even a radio phone-in on the subject in September 2004! There are many different theories around, but the real answer is that nobody really knows. The word "float" seems to have the meaning "delivery vehicle" only when applied to milk floats and, very occasionally, coal floats. However it seems likely that the latter usage resulted from the use of the word with milk, so it would appear that the origins of this meaning of "float" just aren't known! If you know better, or if you have an interesting theory, then please tell me! Add this wonderful site to your favourites: http://www.milkfloats.org.uk