Although the Channel Isles does have its own laws and parliament, it is still technically part of the UK, yet the shipping rate charged in this instance by the WooCommerce plug-in rated the CI as part of the EU.
Some couriers do rate “Northern Ireland, the Channel Isles and the Isle of Man” (as well as the outer Scottish islands) separately from the rest of “mainland” Britain, but the PO does not.
Our client would like to repatriate the Channel Islands and save his customers the additional shipping charge.