The union was established in 1977 as the Abbey National Staff Association, and it received a certificate of independence the following year.

[2] In 2001 concerns were raised about whether the union was 'genuinely independent' of the Abbey National, however, following enquiries, the Certification Officer confirmed its status without the need for a formal review.

[2] It was renamed "Advance" in 2009 after the acquisition of Alliance & Leicester by the Santander Group.

[5] The current General Secretary is Jim Leonard, who has led the union since 2024.

The union organises various levels of representative, members holding 'lay positions' (i.e. unpaid, and additional to work duties).