Thanks Szhjcn...... for both the link, and the ease of spelling your Moniker.
That info was seriously perfect.
I did go back to the shop and discussed the problem, and tried all the boots in the shop.... they all fitted the same.
Clearly this is a common problem, as "Boot selection" obviously helps when there is an option to help you with fit...... but some people (like myself) just have a narrow ankle and ALL boots just fit the same way.
Cutting the links you provided short, The advice summary was as follows:
PROFESSIONAL BOOT FITTER
Great idea where the boots are able to be adjusted.
Must select the best fitting boots available first.
TECHNIQUE
This one was also seemed highly likely, but I will outline this in a seperate post below, it's a bit long for here.
ADDITIONAL SUPPORT
Inner soles
Several posts were made about a range of available innersoles (inculding yourself), again, I guess this is a case of "Each to their own", and "Trial and Error" to get this right.
Inner sole brand recommendations were quite varied, hence the above statement.
Socks
This is a little obvious.
Clearly where the boots are proportionally too big, socks will help.
As the front of the boot is fine, and it's strictly a heel issue, adding socks will just cramp the front of my feet, and adding little to no extra support for the heel.
it's more of a 'quick fix' to over come a boot size problem.
Temporary fixes
jamming paper in between the outer and inner boot wasn't too far off.
Someone mentioned cutting up an old "Mouse Pad" into strips and doing the same thing, and sticky tapping it in.
Being more rigid than paper, yet soft and flexible , this material sounds perfect.
Many posts were made both supporting and condemming this, but it all came down to boot selection again. If the shoe is too soft on the outside, you will just deform your boot and not get the advantage of modification.
Conclusion
Boot selection -
This remains paramount. Take your time, but don't be put off that the boot may not fit correctly, they can be modified to suit later. Select a boot with a firm outter boot, and a removable inner boot. Brands, cost, etc. doesn't matter, the best fit at the time is what matters most.
Technique -
being aware of your stance, and posture when turning.
After this ' Technique ' thing is sorted, I will modify my boots as best as possible.
I have a two week trip away (a week in snowboarding Colorado). If all goes well, I'll post the results of my "experimentation".