I found this quite interesting... Extending caravans in the 1920s...pop tops in the 30s etc. shows the latest ideas in caravans aren't so new...
http://www.oldclassiccar.co.uk/classic_caravans.htm
Harry @ Angela
The units are still the same principal, just the fitouts have changed.
JC.
I find things don't really change just get better even caravans
love my c/v
when all else fails read the instructions cheers