CountryID with Perch Shop & Braintree

I'm having trouble with checkout via Braintree.

I'm currently testing in sandbox and the payment is coming back failed with the following debug message:

...
SELECT * FROM perch2_shop_customers WHERE customerID='11' AND customerDeleted IS NULL LIMIT 1
[1] SELECT * FROM perch2_shop_addresses WHERE addressID=82 AND addressDeleted IS NULL LIMIT 1
[1] SELECT * FROM perch2_shop_addresses WHERE addressID=81 AND addressDeleted IS NULL LIMIT 1
[1] SELECT * FROM perch2_shop_countries WHERE countryID='0' LIMIT 1
No country set for address
[1] SELECT * FROM perch2_shop_countries WHERE countryID='0' LIMIT 1
No country set for address
Payment failed
...

My checkout doesn't require an address, the goods that are being sold through the site are collected from the store so there is no need for a shipping address, but do I still require a billing address for this to work? I was hoping I could just register a user with first name, last name, phone and email (passwordless) and then take credit card details for payment. I also tried setting a default for the country during registration with a hidden field <perch:input type="hidden" id="country_name" value="157" /> but that does not seem to work.

Here is some more of the debug, including the response from Braintree:

...
                    [params] => Array
                        (
                            [transaction] => Array
                                (
                                    [type] => sale
                                    [amount] => 20.00
                                    [orderId] => 35
                                    [paymentMethodNonce] => dab7bd21-bbc9-0e00-2588-d95c0c05ce5c
                                    [billing] => Array
                                        (
                                            [company] => false
                                            [firstName] => Hamish
                                            [lastName] => Irving
                                            [streetAddress] => false
                                            [extendedAddress] => false
                                            [locality] => false
                                            [postalCode] => false
                                            [region] => false
                                            [countryName] => false
                                        )

                                    [shipping] => Array
                                        (
                                            [company] => false
                                            [firstName] => Hamish
                                            [lastName] => Irving
                                            [streetAddress] => false
                                            [extendedAddress] => false
                                            [locality] => false
                                            [postalCode] => false
                                            [region] => false
                                            [countryName] => false
                                        )

                                    [options] => Array
                                        (
                                            [submitForSettlement] => true
                                        )

                                )

                        )

                    [message] => Country name is not an accepted country.
                    [creditCardVerification] => 
                    [transaction] => 
                    [subscription] => 
                    [merchantAccount] => 
                    [verification] => 
                )
...