@slowmotion oh thank god a serious question to answer, (should it be in SC&P though, waggles eyebrows mischievously) Loop pattern in and if still cold a pair of liner socks inside these ones, or a sheet of newspaper in your shoes.
Given that the surgeon has borrowed 650mm of vein (hope you get it back with interest, you could have yards of the stuff to sell on
Ebay 
) you could try
@User21629's scientific experiment and get an result independent of physical or weather variance if you use your freezer, 2 oral thermometers (I guess rectal would do too) and a comfy mat, just open the freezer door and poke your socked feet in with a thermometer in each one; or dangle your feet into from above if of the chest variety; for a set period of time and then having recorded both your observational feelings of coldness and the empirical thermometer reading, allowing your feet to revert to original room temperature and the freezer to revert to normal operating temperature you can try again with the sock reversed to feel and see if the thermometer registers a difference.
You may of course need to repeat with an exceedingly expensive and precise thermometer to overcome the skew that your natural living body temperature would introduce with such blunt instrument temperature measuring devices as mouth or bum ones from boots.
I'm not sleeping much at the mo and I'm off work today, does it show
Edit: typo's. The Mac's autocorrect is odd.
