As I "FINALLY" got this right - I wanted to give back - 1st Post - Hope it works for others!!
I did as OzGadget said - Still no joy.
I then did a combination of what OzGadget AND AnnaLea did....= JOY!
In Summary:
1) Connect your phone to iTunes and back up everything. (inc photos and Vids)
2) Disconnect your phone.
3) Delete ALL the photos from your phone
4) Delete all the photos that are in the deleted photos folder.
5) Once done, disconnect the phone. Turn it off and on again. Then connect your phone back to iTunes and check how much your 'other' is.
6) If like me you had a HEAP (2000+) of photos - you will need to do these steps (4 and 5) a few times to ACTUALLY delete them all. I found that approx half would delete each time (despite selecting them ALL in my deleted items folder)
7) Eventually you should get down to about 400MB of "other".
8) Re-synced what photos i needed from iphoto - and BINGO ! All good.
Now my 64GB iphone 4s has 40GB of Audio and 15GB of images. even some spare capacity !- and other is still around 400MB.
I hope that helps!!
Simon.
PS - Disclaimer - (I also DELETED ALL of my music during a sync too - as i was getting frustrated - Not sure it was actually needed as the issue seemed to be with the images and vids)