David Merrilees

Current Role: Principal Software Developer


Where trust and respect are mutual


Meet David and learn how he’s adapting to life (and work) after the diagnosis of his long-term health conditions. Discover how Tesco is making sure he always has the support, flexibility and freedom to take each day as it comes.


“I'd had a very normal life up until 2018. For years, I’d been working as Lead Developer on Tesco’s websites, across a number of countries. We were exploring ideas that would make the technology platform better for customers, and we’d just completed a really exciting project when my world was turned upside down. As traumatic as it was, it could have been much worse; I can’t imagine an employer treating me better.


I’d had an infection in a wisdom tooth. People say, "Look after your teeth because they’re closely related to your heart health", and it’s true. The infection spread to my heart, causing endocarditis.

“I can't imagine an employer treating me better.”

Endocarditis is 100% fatal without treatment. One July night, it worsened some heart defects I didn’t know I had; a deformed aortic valve and a hole in my heart. It led to my aortic valve collapsing and enlarged the hole. That meant acute heart failure, my heart suddenly couldn’t pump enough blood around my body. This caused a seizure. I had more seizures before I was rushed to hospital, including while I was being loaded into an ambulance.


I had antibiotics to kill the infections, emergency open heart surgery to have a prosthetic aortic valve implanted and the hole in my heart patched, which saved my life, but I kept having seizures where I'd lose consciousness. The medical team thought it was a cardiac issue, so they implanted a heart monitor in my chest. When I had more seizures, they saw what was happening to my heart, which had been ‘pausing’. They fitted me with a pacemaker, which prevented my heart pausing, but I kept having seizures. Eventually, I was diagnosed with a form of epilepsy called temporal lobe epilepsy, caused by brain damage.

“It can feel difficult to do ordinary things that people take for granted.”

Neurologists referred to the brain damage as scarring, which can happen when there isn’t enough oxygen reaching the brain. As a result, I occasionally have seizures where I lose awareness. When I regain consciousness, I can't remember what I was doing or where I am, and I lose memories. It's quite a subtle thing, not a violent seizure, so I don't shake. They look like I'm either asleep or distracted. It’s happened during meetings on video, and when I’ve been in the office, but my colleagues are aware of the situation and know what to expect.


I have them in clusters. It usually starts with a big one. I’ll have a strange sensation of déjà vu and a rising feeling. I don't quite have the words to describe it. Apparently, that's a common symptom with this type of epilepsy. It's like you’re having a dream except I’m awake when it begins. My mind starts telling me a story but I can’t control it, then I’ll lose awareness completely. Sometimes I don’t lose consciousness, but I can’t respond to anyone who’s talking to me.

“It affects every aspect of life now.”

I’m not allowed to drive, bathe, swim or drink alcohol. The medication has side effects as well, impacting my balance and mood. It affects every aspect of life now. I look reasonably fit, I guess. But with a hidden disability, it can feel difficult to do ordinary things that people take for granted, like taking the kids out on their bikes. Should I cycle with them? What if I lose consciousness and fall off? Are they going to be alright if I suddenly need to lie down? Or, if I take them to school, and I have a seizure in the playground, what are the other kids going to say to them?


It starts to make you feel excluded and outside of normal society. You can feel a bit left out, which affects my confidence. But people at work have only ever been very supportive. Naturally, they’re curious. They want to know more and make sure I’m ok. Initially, I was quite stoic and reticent to talk about these issues, I didn’t want to tell anyone. But I'm encouraged to talk about this openly. My colleagues have only been encouraging and accepting.

“People at work have only ever been very supportive.”

My manager has always been very accommodating. I have frequent medical appointments, which can impact the working day, but I’m trusted to manage my own time. I was encouraged to work from home before the pandemic arrived. When I do come into the office, my manager makes sure that I travel safely. I’m supported to decide what's best for me. I hope that I reflect the trust Tesco have shown in my work, and it’s mutually beneficial.


As I've continued to go through all these bizarre medical traumas, I’m still able to help shape technology at Tesco. The neurological, psychological and physical issues I face would be barriers for many employers, but Tesco focuses on outcomes over outputs. They know that a focus on outputs can have a harmful effect, leading to blame, fault finding and micro-management. Focusing on outcomes means that Tesco shifts the language towards acceptance, practical solutions and altered expectations. And that works for me.”

If you want to work somewhere you’re trusted to deliver, and the respect is mutual, talk to Tesco. We’ll offer the support that lets you do your best work, plus the flexibility that fits your life.

To explore our latest Tech opportunities, click here

Find out more about...

Opportunities to Get On

Create a successful future as part of our team.

More stories like David Merrilees's...

Sajid Rashid

Sajid Rashid

"My work-life balance is perfect!"

Matus Turan

Matus Turan

“There are so many opportunities to develop and learn.”

Search and Apply

Explore our opportunities in your area and across the UK. Find your place to get on in a job you love, everyone is welcome.