I have a working system.
I had a look at the file system and found rc0.d up to rc6.d, rcS.d and init.d. No rc.local.
After a quick search I found details on creating an rc script.
I created a file: "link_serial" in /dev/init.d/
In the file I placed :-
ln -s /dev/ttyAMA0 /dev/ttyS1
I then made the file executable
chmod 755 /etc/init.d/link_serial
I executed the command :-
update-rc.d link_serial defaults
This brought up a warning :-
script 'link_serial' missing LSB tags and overrides
but I don't think this is a problem in this case.
The above command created links in rc0.d to rc6.d but not rcS.d
As I understand it, I only really need a link in rc2.d. Should I remove the other links ?
After reboot, ttyS1 was available for use.
So I think this has got me going. If you can see any obvious errors or bad practice I'd love to know what I've done but otherwise I think I'm hot to trot.
So thanks for your help guys.