To link your HSBC current account you will need:
This is either your IB number or a unique username you created and you use to log in to your Online Banking.
2. Memorable Answer
This is the answer you have to enter when you log in to your Online Banking WITHOUT SECURE KEY.
This is your online banking password. HSBC asks for 3 random characters but Plum requires the FULL one.
If you have forgotten your Online Banking log on details you can find the instruction from HSBC here.