On Monday night, Moritz Erhardt, 21, was found dead in his east London flat. He was a week away from finishing a summer internship at the London office of Merrill Lynch. The exact cause of his death is not known, but it is claimed that Mr Moritz had worked three “all-nighters” in a row before his death and was determined to earn himself a full-time role at the bank.

I too interned in the London offices of Merrill Lynch before accepting a job on the graduate scheme. I was one of 30 bright, keen twentysomethings who were opting to spend the summer hunched over desks, deep in financial equations. Like Mr Erhardt, I threw myself into the internship programme, relishing the challenge that awaited me.

We thought we knew what we were letting ourselves in for. The long hours and hard work were no secret among university undergraduates. Even before I joined the firm I’d heard tales of junior bankers collapsing from exhaustion and analysts who slept under their desks. Secretly, I think we wanted to be a part of this strange, exclusive club. We were young, impressionable and eager to please. We wanted to feel important and we wanted to justify the £6,000 we were earning that summer.

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During our internship, all-nighters were a rite of passage. We discussed them in the Merrill Lynch canteen as we ate our free dinners each night. Outwardly, we expressed our loathing, but in reality, we were proud. You weren’t deemed a “proper” banker until you’d worked through the night.

We bought into the idea that fulfilment would come from “succeeding” in this crazy game. For seven weeks, our world shrank to one square mile and during that time, nothing else mattered. We forgot about family, friends, pets, birthdays… We could tell you the value of the FTSE but we couldn’t say how our grandmothers were doing. Hundred-hour weeks were standard. Many of my peers treated Saturdays as a working day and then tried to take half of Sunday off to recover. Some didn’t even bother to go home when they worked through the night; they just showered in the in-house gym, bought a toothbrush from the in-house shop, grabbed an espresso from the in-house Starbucks, and they were good to go for another day.

Of course, we knew this wasn’t productive in the long term. But the adrenaline (combined with caffeine and taurine – or cocaine, in the cases of many full-time bankers) would see us through.

One night, my flatmates and I were woken by the doorbell at 2am. It was a company car, waiting to take me back into the office to “check some figures”. With the “checking” complete, the rest of my night was spent awaiting further instruction. That’s when sleep beckoned.

There is a lot of waiting around in banking. It’s the financial equivalent of being “on call”, except that you’re not saving lives. The truth is, interns (and to a large extent, analysts) are not qualified to take on responsibility. I certainly wasn’t, being half-way through a degree in engineering. The tasks undertaken by interns and analysts are very mundane. We spent our nights and weekends cloning PowerPoint slides, sifting through annual reports and picking through excessively complicated financial models in Excel, some of which never got used.

There was a culture of vindictiveness that trickled down the hierarchy. VPs would dump work on associates, who would dump it on analysts, who, at the end of the working day, would dump it on the intern with a deadline of 9 o’clock the following morning, even if it was needed for an afternoon meeting. And often, the afternoon meeting would be cancelled and nobody would think to tell the intern.

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Working late was a surreal experience. Once the senior bankers left for the day (which most of them did around 6-7pm) it was just us, the minions, tapping away at our keyboards, sweating as the air con went off for the night, occasionally plunged into darkness as motion detectors on lights failed to register our movements. If you squinted through the tinted glass windows, there were small signs of life outside: other junior bankers and lawyers cracking on through the night in their matching glass office blocks.

We worked hard, but we also played hard. Throughout the summer, we were plied with perks: cocktails at the Tower of London, drinks at Madame Tussauds, dinner at Coq d’Argent, dragon-boat racing on Monkey Island… and that was on top of the free meals, company cars and central London accommodation. At the time, we felt valued, as though this was our reward for all the hard work. In retrospect, it was more like absent parents buying their children’s affections with lavish gifts.

The firm ticked all the boxes on the HR front. We were assigned “buddies”: full-time bankers to whom we could go with any questions or concerns. (Nobody I knew ever approached their “buddy”; bankers didn’t have time for questions.) We attended lectures and talks on the values of the firm (Client Focus, Respect for the Individual, Teamwork, Responsible Citizenship and Integrity) and we were taught the procedure for surfacing concerns. (We found these laughable at the time; with hindsight, they were ludicrous.) The reality was that we had all signed away our right to the statutory working week; for one summer, we were the property of the firm.

We didn’t mind. Like Moritz Erhardt – who was said to have told prospective employers that his upbringing taught him to “always be driven to be good at everything” – we wanted to impress. Looking back, I suppose this was one of the key criteria sought out by the banks’ recruitment teams. They wanted “all-rounders” – not because they valued our skills on the football pitch or on stage but because a jam-packed CV was a sign of a young person who would do whatever it took to succeed.

When it came to it, Mr Erhardt was not “forced to work through the night”. We weren’t forced to do anything. We worked through the night because we chose to. We were keen, naïve undergraduates, desperate to make our mark on the world.

We competed for places on the internship via stressful all-day assessments. I can still remember the mental arithmetic questions fired at me during my interview and the tense atmosphere in the plush, carpeted lounge where we sat in our starched new suits between tests.

Many of us had applied to more than one City firm. There was a strict hierarchy: the American firms were seen as the best, Japanese a close second, with European banks seen as a last resort. I remember turning down another offer when I found out I’d been awarded an internship at Merrill Lynch.

The competition didn’t end when we won our internships – quite the opposite. Throughout the summer, we were constantly reminded that we were effectively living out a seven-week job interview. As our internships drew to a close, rumours started to circulate about how the bank would offer full-time roles only to the very hardest-working interns. Our peers became our enemies and we quickly picked up tricks from the bankers, embarking on “face time” (pretending to be hard at work even when you’re done for the night), back-stabbing and the long-hours game, sending out department-wide emails in the middle of the night to show how hard we were working. We all desperately wanted to be rewarded with the salary and prestige of a job at the end of it.

In the event, nearly all of us were offered full-time roles for the following year and I, along with everyone else, accepted without hesitation. Of course I wanted to live this life. I wanted to be a banker. I wanted the chance to go all the way to the top.

Well, it turned out that no amount of money or prestige could make up for the exhaustion, the misery and the lack of control we all had over our lives. I broke after only a few months, but it took others a few years to realise this.

Moritz Erhardt was universally regarded as a kind and generous individual. He will no doubt leave a hole in many people’s lives. We may never know the exact cause of his death, but perhaps his family might take solace in the fact that, by shedding light on the exploitative practices employed by our financial institutions, he is continuing to do good work.

I hope this terrible tragedy serves as a wakeup call – not just to employers and policy-makers in the investment banking community, but also to employees. The money is just an anaesthetic; it might work for a seven-week internship or perhaps even longer, but it wears off in the end.

Polly Courtney is the author of ‘Golden Handcuffs – the Lowly Life of a High Flyer’, a semi-autobiographical novel based on her life as a junior investment banker.