Thank you everyone for your immensely helpful comments. Jan, your pic shows it really clearly - thanks.
Sharley, please tell Colin I am really grateful for the info...
I must say, I've also done a variety of jobs, and it is useful for having a feel for different things, rather than just doing one job all one's life. Gives us wider knowledge. A bit like we were saying that divorce and related experiences were useful for writing, even though they may not have had much merit in other ways.
I can now continue my scene, feeling fully in the know about transit vans...
Deb