Russell, you are exactly right, at least according to the research of one man here in the US. His name is Jan Heine and he publishes a magazine called Bicycle Quarterly. His real world research, actual bikes on real roads, found that there was less rolling resistance from wider tires and less pressure. A synopsis is herehttp://www.bikequarterly.com/images/BQTireDrop.pdf
That's not what the article says. His words are: Our tests of tire resistance have shown that tire resistance is high at very low pressures. As pressures increase, tires roll faster, but the performance levels off at a certain pressure. Beyond this point, higher inflation brings only negligible performance improvements.
It doesn't say that a wider tyre with less pressure made less rolling resistance.