A couple tips you could try from looking at your script.
The first step I’d take in debugging is checking the output of the subprocess call method. You can do this using the check_output method. This will give you more information about whether the output succeeded or not and also output from executing.
Also, the call method takes a list where the first element is the command and subsequent elements are the arguments. So you could try:
subprocess.call(["C:\\Python27\\python.exe", "C:\\Test\\Scripts\\Test.py"], shell=True)
Another option for building paths that’s OS independent is to use os.path.join. That should give a valid path to the file without having to escape backslashes and all that.
Hope this helps and good luck!