The HSBC-owned telephone and online bank is currently looking for a replacement for Mullen, whose responsibilities are currently being shared between First Direct’s head of brand communications Lisa Wood and the marketing team at HSBC head office.
Mullen was behind the Leeds-based financial services firm’s customer recommendations site, Little Black Book.
He also oversaw a recent television campaign featuring Peep Show actor Matt King which aimed to highlight the bank’s customer service credentials.
First Direct also launched a major push into social media earlier this year, promising a ‘Facebook for banking’ as it looks to use social networks as a channel for dialogue with and between customers.
HSBC is also currently looking for a replacement for UK marketing director James Boulton after he stepped down at the start of the year.