[O] Separate Org file from Subtree

[simon]

Hi there,

I think I must be missing something.

I have  a collection of articles in one org file (under separate
headings). I can export these as a subtree using Org's normal export
function as html etc., but I want to export the selected subtree as an
individual org file using the properties under each heading.)

In other words I want to export this subtree ...
* DONE Article One
:PROPERTIES:
:EXPORT_TITLE: An Interesting Article
:EXPORT_AUTHOR: Simon Jones
:EXPORT_FILENAME: an-interesting-article
:EXPORT_DATE: 2015-02-16
:END:

Article content ....

into an Org file entitled 'an-interesting-article.org' that looks like
this ...

#+TITLE: An Interesting Article
#+AUTHOR: Simon Jones
#+DATE: 2015-02-16

Article content...

Can anyone help me with this? I'm very sorry if I'm missing something
obvious.

Simon.