Executive leadership.

An Executive Leadership Team comprising of the following members oversees the day-to-day operations and ongoing development of Defence Bank.


David Marshall.
BCom, Post Grad. Dip. Com, Executive Development Program.
Chief Executive Officer.
David Marshall

Skills and experience.
David commenced as Chief Executive Officer of Defence Bank in February 2018. He has initiated a major ‘member experience’ transformation program aimed at reducing member effort at every touchpoint.

David has spent 35 years in the financial services sector in Australia and New Zealand. During this time, he has led major retail and business banking divisions in major and regional banks.

Prior to his appointment as CEO of Defence Bank he was CEO of Hume Bank, a leading Mutual Bank in Regional NSW/Victoria. He is a passionate advocate for the member-owned banking sector and its role in the contemporary financial services landscape within Australia.

David grew up on a farming property in New Zealand. He studied at Lincoln College (Canterbury University), London Business School and Wharton Business School.


Dean Barton.
Chief Financial Officer.
Dean Barton

Skills and experience.
Dean joined Defence Bank as Chief Financial Officer in 2011. His primary responsibility is the bank’s financial and regulatory reporting, management reporting and budgeting, funding and capital management. He also acts as Company Secretary to Defence Bank.

Dean has more than 20 years’ local and international experience in financial roles including Financial Controller for ME Bank, and Asia-Pacific Regional Financial Controller for GMAC Financial Services.

Dean is a Fellow of CPA Australia and the Financial Services Institute of Australasia, and a graduate member of AICD. Dean holds a BCom from the University of Western Australia majoring in Accounting and Economics.


Kristen Bugeja.
Chief People Officer.
Kristen Bugeja

Skills and experience.
Kristen Bugeja leads the People & Capability team at Defence Bank. She has more than 20 years’ experience in the financial services sector.

Kristen has had extensive experience in delivering the cultural change that underpins Defence Bank’s business strategy. She has successfully driven change across a range of people functions including career development, talent and leadership programs, and employee engagement.

Under her guidance, Defence Bank was a finalist in the Australian HR Awards 2017 for ‘Best Change Management Strategy’ and in the Australian HR Awards 2016 for ‘Employer of Choice’.

Kristen is a certified member of the Australian HR Institute.


Sean O'Donnell.
MBA, B.Bus, Dip Fin Adv, GAICD
Chartered Banker
Chief Digital and Technology Officer.
Linda Craven

Skills and experience.
Sean joined Defence Bank as Chief Digital and Technology Officer in October 2023. He is an experienced senior executive and Non-Executive Director with extensive experience in the banking and technology sectors. He has held senior executive roles with global information technology firms. His banking career has seen him hold senior leadership roles in both major and regional banks.

In his current role Sean leads Defence Bank’s Business IT team. His team is focussed on enabling Defence Bank’s digital transformation with an emphasis on member experience, risk management and information security.

Sean strives to make a contribution to the wider community. He is an ambassador for Melbourne City Mission and its flagship fund raising event, Sleep at the ‘G. In addition he is an adjunct senior lecturer at Central Queensland University where he lectures on Banking and Finance as part of the University’s MBA programme.


Marnie Fletcher.
B Com, B Arts, Post. Grad. Dip Applied Information Systems.
Chief Member and Growth Officer.
Mano Simos

Skills and experience.
Marnie joined Defence Bank in February 2021 as Chief Member and Growth Officer. Marnie brings with her 23 years experience in banking across a range of financial institutions including Esanda, ANZ, Westpac and ME. Whilst having worked with a broad spectrum of customers from Institutional through to Retail, her passion is for the every day Australian and helping people create financial freedom into retirement.

Marnie has had extensive experience delivering transformation programs, risk management, driving growth and leading teams at scale.

Marnie leads our Frontline teams as well as our Lending Operations and Member Services divisions. These teams have a direct line to our members and are the front face of Defence Bank, serving those who protect us.

At home, Marnie is a mum to 3 daughters and is an active role model in helping leaders & teams to find energy in the creation of harmonious work life integration - and being the best versions of themselves.


Michael O'Reilly.
BA, Grad. Dip. Marketing.
Chief Marketing and Product Officer.
Michael O'Reilly

Skills and experience.
Michael joined Defence Bank as Executive Manager of Marketing in December 2017. He brings with him more than 22 years of product and marketing experience within the financial services sector.

Prior to joining Defence Bank, Michael was responsible for developing marketing strategies across a range of mutual and major financial institutions including Teachers Mutual Bank, Community First Credit Union, CommSec and Lloyds TSB. Michael’s experience also includes working abroad as a Product Manager for Lloyds TSB.

Michael leads the day-to-day marketing functions with specific responsibility for brand, marketing strategy and product.


Mano Simos.
BBus Accounting, Grad. Dip. Banking & Finance, GAICD.
Chief Risk Officer.
Mano Simos

Skills and experience.

Mano has been Chief Risk Officer at Defence Bank since October 2013. He is primarily responsible for the development and oversight of the bank’s Risk & Compliance Management Framework. Mano leads a team who collaborates with executives and their teams providing guidance and advice on the implementation of these frameworks. This second line function remains independent of the business and provides the Board and the Risk & Compliance Committee with assurance and insights around the management of our current and emerging bank-wide risks including credit risk oversight and financial crime.

Prior to joining Defence Bank, Mano worked at NAB - directly with the Business Banking CRO and with the Group Executive Business Banking as secretary to its Risk Committee and responsible for risk governance.

Mano is a graduate member of the AICD.