Printing & Opening PDFs using Flex GP Widget

I have a geoprocessing service that gathers some user-inputted parameters, does some processing and then creates a PDF output showing the results (from a MXD template). Most of the processing is standard modelbuilder, but the print bit at the end is a python script that references the MXD template and generates and opens up the PDF.

It all works fine when run from Catalog but when it is run as a service, I can't get the PDF to pop up. I know that the rest of the process is working (because I can access the results via a popup) and the process does not return any errors, but I can't get the result PDF to open up in the browser.

I have been using os.startfile and webbrowser.open to open the PDF (both of which work in catalog) but I know that they have some issues when being run with arcpy. I have used the workaround wrapped suggested here but it hasn't solved the problem.

So, does anyone have any smart ideas as to how I can get a PDF output to automatically open in a browser when it is the output of a GP service in a Flex application? Happy to post screenshots/code if it would be helpful.

I am running Server 10.2.1 and Flex 3.5

Many thanks!
Natalie Scott
Interpret Geospatial Solutions