Braintree Transaction Details:

Braintree Transaction ID: 6j37brpm
Status: submitted_for_settlement
Instrument Type: credit_card
Processed on: 2019-05-27 06:13:51 am UTC
Currency: GBP

Initial Processor Response Details:
Authorization Code: 031963
Response Code: 1000
Response Text: Approved

Basic Fraud Details:
CVC Check: I
Address 1 Check: I
Postal Code Check: I
AVS Check: 

Note: You are using the Dropin UI and we expect the Address 1 Check value to be an I (Not Provided).  This is because the Dropin UI does not collect the Address from the customer.  Since the value is not collected, Braintree bypasses the checks.