I am beginning to suspect the device is behaving strangely. I have set location to yes in the InAppBrowser and it is showing what appears to be the correct uri for the pdf.
It begins:
[url=http://data:application/pdf;base64,JVBERio]http://data:application/pdf;base64,JV...[/url]...
I am guessing that this is the right uri format for a pdf file, so why isn't it being displayed?
I guess I need to test on another device, when i can get hold of one.