I found a bus up for sale on Ebay in the UK, and thanks to some advice from Zombie Ad I decided to take a risk at not knowing how it would size up with every thing else and buy it.
I think the bus is 1:50 scale.
Thanks to the excellent advice (Thank you Zombie Ad!) I now have a bus to add to my games :-D
I am amazed at how many more vehicles can be purchased in the UK, and how much cheaper they are. Most sellers will ship internationally, but there are a few missing out on sales because they wont ship outside the UK.