Your Reading List & recommendations

Meet the people behind O2: Tom Mullen

A series that looks at the people behind the technologies we support across Britain.

At O2 we employee thousands of talented individuals to support our diverse customer base. From front line staff working in store with the latest mobiles, accessories and consumer products, to technical specialists who can design your integrated mobile, Wifi and fixed-line networks, as well as identify the right managed services and digital solutions for your organisation. At O2 we believe that the solutions we provide are only as good as the people that help you make the most of them.

Check out what jobs we have available that might be a good fit for you

Tom Mullen, O2’s Head of Cyber Security

What do you do at O2?

I’m Head of Cyber Security, which involves ensuring that we have the right systems and controls in place to protect our systems and customer data. I am also on the Security Incident Management Team to respond to major incidents.

I lead on government initiatives like TBEST, which is an intelligence-led threat penetration test. O2 was the first Mobile Telco to work with OFCOM, The National Cyber Security Centre and the Department for Digital, Culture, Media & Sport to develop and run this program.

How did you end up doing what you do, and why O2?

I joined the army after school, but found there was no obvious career path for me once I left. I joined BT as a trainee maintenance engineer and, after two years in the role, I discovered an interest in computing. I went to college in the evenings to study for a City and Guilds in computing and then my Higher National Diploma.

Over the next three years I moved into network cabling, then software support, hardware support, special faults investigations, and network design and support. It was whilst I was managing a team maintaining networks and systems in the south east that I witnessed the evolution of the internet and recognised the impact it would have on our future.

My career changed when I applied for a role as Head of the Computer Emergency Response Team at BT. I was interviewed by a real visionary, Dr Claudia Natanson, who was previously the Chief Security Officer at the Department of Work and Pensions. She gave me the role of setting up an e-crime team, the first end-to-end computer investigations team in the UK, with technical experts, forensic experts and investigators. In its first year, we worked with the police to arrest numerous people for hacking and other computer crimes and offences. The team continued to grow and is now a critical area for the company.

What gets you energised in the morning for the day ahead?

Getting up to do a job I love. My career advice to anyone is to make sure you choose a job you love. Put the effort in, you’ll enjoy it more, and success will follow.

What is your biggest pet peeve?

Negative people who tell you that you can’t do something. There’s always a solution. Always a way forward.

What’s been your proudest achievement so far in your career?

There have been a few, but being selected by my industry peers within FIRST (Forum of Incident Response and Security Teams) to serve on the steering committee and board of directors is right up there. Helping to shape an organisation alongside some of the leading security experts in the world was a real honour.

What’s the one small thing in life that always makes you smile?

When something happens that makes people finally understand security and the need for it – that eureka moment when the penny drops.

How do you see your role evolving in the future?

When the Internet of Things (IoT) is enabled by 5G, we can expect to see new types of cyber-attack using the increased bandwidth to target companies and consumers. My role, along with my peers, will focus on the job of securing the IoT.

How do you switch off and wind-down?

I love most sports and being outdoors. I ski, hike and dive. I support Chelsea and Scotland, having been born in Glasgow.

What does a healthy relationship with technology look like for you?

Seeing security as a business enabler.

How long would you survive a full digital detox for?

A week is the best I have ever managed. Holidays are always a challenge because my wife hates me looking at email.

With O2’s focus on creating customer experiences – what’s the one gig/show that changed your life?

I love a wide range of music and try to play the guitar. The Three Tenors at Hyde Park were just amazing, but so were Pink Floyd and Luther Vandross at Wembley.

What are you most excited about that the future will bring?

5G and IoT, if secured properly, can change the way we live for the better. I can’t wait to see the innovation that this will bring.


Tom is always pleased to talk with anyone about cyber security, so do get in touch. You can connect with him on LinkedIn and follow him on Twitter.

All articles


Public sector

Safe & secure


Tech advice

Work smarter