This is what it was like to witness the moment Benedict XVI became the first pope to resign in 600 years

February 11 is a holiday in the Vatican. It is the day when the Holy See celebrates the settlement in 1929 of the so-called “Roman Question”, the resolution of the 59-year stand-off between the Kingdom of Italy and the Holy See after the fall of Rome in 1870 to the Kingdom’s troops and the effective end of the ancient Papal States in central Italy.

By chance it was also the day Pope Benedict XVI chose to resign.

The date had been scheduled for a small consistory, comprising midday prayer and the announcement by Cardinal Angelo Amato of some beati due to be promoted to saints. There had also been a little gentle buzz for some time in the Roman Curia about the Holy Father announcing one or two important changes then, perhaps near the top of the administration, but these kinds of rumours circle like the seagulls around the Vatican’s Belvedere: they come round frequently, make a bit of noise and go away again. In other words, as in most places, nothing happens until it happens.

There was no indication that this day was going to be any different. It was also a holiday, and although the rest of the Curia was enjoying a rest, the few people around the person of the Holy Father, including myself, were to be on duty in the Apostolic Palace’s Sala del Concistoro to welcome him as he went to pray with the cardinals present in Rome and to go through the short ceremony.

As a Prelate of the Anticamera, a kind of aide de camp, who assists the Holy Father’s principal guests and makes sure everything goes according to plan when the great and the good come to call, I met the Holy Father before the ceremony began. As usual he came down by a private lift from his apartments with Archbishop Georg Gänswein and Mgr Alfred Xuereb, his two secretaries. He looked well but tired and greeted us in the usual way. As this was a day of particular solemnity, the Master of Ceremonies was present. Archbishop Guido Pozzo, the then Almoner, was also there.

Once the Holy Father had been readied for the Liturgy of the Hours, we all followed him into the Sala del Concistoro to pray with the waiting cardinals. We sang midday prayer for the memorial of Our Lady of Lourdes (February 11) then Cardinal Angelo Amato made his announcement regarding those soon to be promoted to the altars. So far so good.

The Holy Father then took the floor. This was the first time I had sat in a consistory, so I had no idea if this was normal or not. He spoke in Latin, so a greater effort than normal was going to be required by all of us – Italian being the normal language of the Curia – so a little strain was evident as we tried to grasp where he was going.

Within seconds it was clear what was happening. This was no ordinary address. He did not speak about the consistory and the soon-to-be saints, or a few changes in administration, or the anniversary of the Lateran treaties, or the end of the historic dispute with Italy. Instead, he made history. I felt my stomach turn over as I realised that here before us was something not seen for centuries: the voluntary resignation of the Roman Pontiff.

It seemed that, in slow motion before me, an assistant television cameraman put his hand to his mouth in a cartoonlike gesture of astonishment, the monsignor sitting next to me started to sob quietly, Archbishop Gänswein’s shoulders seemed to drop. The cardinals leaned forward to make sure they understood precisely what was being said and I found myself checking that my jaw wasn’t dropping open. Then there was silence.