Oops, that would be the FAR more logical place to put it. Thanks, I have done that now (and removed my mistake) as I want to keep things as standard as possible.
This is better as it tries to work (albeit with a network error) even on “start in desktop browser”.
In that case
<script src='https://storage-introduces-owlishly.volt.live/api/client/volt.js' > should be appended with
</script> (without which the desktop deployment throws up errors).
Ps: No, I didn’t need to modify config.xml … that just modified itself when I deployed to PhoneGap .