The first direct lab site was launched in August to give visitors the chance to see what the bank is planning and critique it through a comment facility and forum.

The initial plans up for discussion included a Web site re-design, a consultation on the use of QR codes and an early version of a mortgage comparison smartphone app.

Now the bank is asking customers to view a number of design options for its next debit card, showing images of a card featuring a matt black front with sparkle ink backing and logo, and a silver version in sparkle ink.

After four days live on the site, 1204 people had added their comments, including 46 on Tuesday alone.

Previous tests on QR codes and Web site design pulled in 604 and 308 comments respectively.