function get_free_shipping_minimum($zone_name = 'England') {
    if ( ! isset( $zone_name ) ) return null;

    $result = null;
    $zone = null;

    $zones = WC_Shipping_Zones::get_zones();
    foreach ( $zones as $z ) {
        if ( $z['zone_name'] == $zone_name ) {
            $zone = $z;
        }
    }

    if ( $zone ) {
        $shipping_methods_nl = $zone['shipping_methods'];
        $free_shipping_method = null;
        foreach ( $shipping_methods_nl as $method ) {
            if ( $method->id == 'free_shipping' ) {
                $free_shipping_method = $method;
                break;
            }
        }

        if ( $free_shipping_method ) {
            $result = $free_shipping_method->min_amount;
        }
    }

    return $result;
}