For some countries there is a small shipping fee.
Where there is a shipping fee then there is also a minimum order price to earn free shipping*. This minimum order price is £40- for other currencies use this number through the current rate of exchange to get to the wanted currency.
Great British Pounds (GBP) to United States Dollar (USD).
£1=$1.30, £40= $52
Therefore $52 is the minimum order price for free shipping.