It is 7am on Judgment Day. I manage to switch off my alarm clock by means of clear verbal instruction as we are now owners of an Echo Dot and Alexa does not approve of mumbling. Then, I lie in bed for a few moments, still disbelieving that I will be in the Supreme Court today.

Somehow, at the very end of my pupillage, I found myself instructed together with Lord Garnier QC (4 Pump Court) and Tom Cleaver (Blackstone) to act for Sir John Major in the prorogation case, intervening on the side of Gina Miller. I had indicated that I was interested in public law cases, but when asked whether I would want to work on a judicial review, I could not have imagined in my wildest dreams that it would be this judicial review. After slightly frantic weeks with little sleep, much time in front of my screen and three days of hearings, the justices will hand down their judgment. Definitely not an ordinary day.

Working as the junior junior on an historic and controversial case with esteemed barristers and the talented team at Herbert Smith Freehills, there is always a fine balance to be struck between being helpful, speaking one’s mind and not being the pupil with grand thoughts about the constitution. I probably did not always get this completely right. Shutting up is not exactly my core competence, but I tried. Luckily, everyone was as excited as me to be involved with this case and my phone was buzzing non-stop with drafts, new ideas, updates on court times until late at night. This is partly what has landed me with Alexa. Apparently, it does not help your sleep to be constantly glued to your phone – or so I am told. The sleep gurus and my partner are probably right about this.

I have a glass of grapefruit juice and make sure my laptop is charged. Then I nervously consider my wardrobe. Nothing seems Supreme-Courty enough for the big day. Eventually, I opt for black and white, which my partner has affectionately labelled my ‘penguin look’. It is good that my efforts to be a proper barrister are not always taken too seriously at home. From behind a wall of judicial review books and the Economist, my partner asks me how I feel about the case. Cautiously optimistic. The three-day hearing seems to have gone well and the questions by the justices seemed helpful, but you never know. I have by now completely talked myself into believing in our case.

I make my way to Westminster and walk past the people camped outside the Supreme Court. Most seem to favour the case against prorogation. Some carry placards to that effect and a blue dinosaur onesie with yellow stars sewn on probably also indicates support. The security guard at the door is friendly: he recognises me and finds my name on a list and gives me a red badge that says ‘Lawyer’. I then walk up to the second floor where the Major team has its preparation room, located conveniently close to the main courtroom and with a huge screen to watch the proceedings. It is also a kitchen, which we have kept well stocked with crisps and chocolate throughout the hearing.

With so many lawyers involved in this case, seating in the court room is in high demand. But not only is our senior solicitor deeply knowledgeable in public law, he also turns out to be highly skilled in negotiating more seats. I learned from his skills and managed myself to wrangle a little more space in the court on previous days, assuring others that, being rather short, I wouldn’t obstruct their view. Today, Tom Cleaver cannot be here and I have a seat at the table. It is truly fantastic to be ‘in the room where it happens’, to quote Hamilton. In the Admin Court, Lord Pannick had opened with a joke about this being the first case for the pupil on the claimant’s team (I can empathise with that) and he had assured the pupil that not every case would be like this. Probably no case will ever be quite like this again.

I have a short chat with one of the young female barristers next to me. Throughout this legal drama, I have been greatly encouraged by meeting many strong women. Joanna Cherry and Gina Miller, of course, but also the lawyers working behind the scenes, not least on my own team. It has rightly been pointed out that the claimant and defendant counsel teams did not feature any women and it is notable that no oral submissions were made by a woman, but I take heart from seeing more female Supreme Court Justices and many women on the intervener teams. The Bar definitely still has some way to go in terms of gender balance, but, as with the case, I am optimistic.

Lady Hale starts reading the summary of the judgment and as she finishes, restrained cheering breaks out. The prorogation was unlawful, null and void and Parliament has effectively not been prorogued. It came as a surprise to receive not only such a forceful, unanimous judgment but also these specific pronouncements on remedy. Articles and books will be written about the wider implications of this for public law, for the importance of constitutional principles in judicial review and for the power of the Supreme Court.

We retreat to our kitchen, blue, printed judgments in hand, and hear the crowd cheering outside. We digest the outcome and call our client. My inbox fills up with messages from happy friends and colleagues who have been following the news and I inform our great team of clerks and my pupil supervisor of the result, even though they surely already know. They have been very supportive throughout, keeping my diary free and discussing the case at length.

We leave the building without incident. On one of the hearing days I had walked out right after the Miller team when some protesters were pushing up against the police, shouting ‘shame’ and ‘traitor’. It was not a great experience. But today, the crowd seems happy and I walk back to Chambers with Edward Garnier.

Several weeks ago, for the first team call on the case, I visited Edward’s beautiful room for the first time, clutching my blue legal notepad. Art, armchairs, the board from One Brick Court and, particularly intriguingly, the Solicitor General’s red box decorate his room. At that time, I felt somewhat in over my head, but the key, as one advocacy tutor told me once, is to be like a swan – gliding along on the surface while furiously paddling underneath. (I am still working on the gliding part.) Outside Edward’s room on our return from the Supreme Court, he winks as we part: ‘Not a bad way for me to end my career and for you to start yours, right?’ Although I couldn’t agree more, I am sure that he is not at the end of his career just yet.

More than one person had advised us to ‘crack open the champagne’, but it is a bit early and we decide to save that for later. Instead, I celebrate by deciphering a 10-page hand-written statement composed by an angry litigant in person. I then have a late lunch (pasta from Guido’s on Chancery Lane) with my co-pupil who has become a good friend. Then it is back to my desk and, buoyed with energy, I say yes to probably too many new enquiries. In the evening I celebrate with a nice dinner and a bath and look forward to a long weekend in Ireland, where I intend to breathe fresh air, see some cliffs and sleep.