Msendoo and Iveren were beautiful little girls.
Msendoo and Iveren were successfully separated
They lay in the hospital bed, having arrived from a remote part of Nigeria two days before, with their smiles captivating the nursing staff.
I knew that it wasn't going to be long before I too joined their growing band of admirers.
But Msendoo and Iveren were no ordinary patients.
They were conjoined twins, fused together from the breastbone to the navel and sharing major organs like the liver.
They had journeyed many thousands of miles to Great Ormond Street Hospital to see if they could be separated, allowing them to lead individual, independent lives.
It was going to be an operation that would take the parents, Isaac and Nguveren, on an emotional rollercoaster of epic proportions.
However, for Professor Lewis Spitz, one of Britain's foremost paediatric surgeons, it was to be his 24th and last separation before he retired.
"The parents have given birth to an anomaly. Staying joined together is really not an option", he said.
It was also going to be an operation fraught with danger and dilemmas.
"You've got two potential survivors but any catastrophe could happen during surgery means they both may die. It is very tense."
Four months later, I walked into a London hotel knowing that something special was about to happen.
Sometimes, as a documentary maker, you just get a feeling - and today was one of those days.
Msendoo and Iveren before surgery
Over the previous months we had met some of the team's past cases of conjoined twins.
Knowing that 'the Prof' as they call him, was about to retire, they were keen to share their experiences; today we were bringing them together for the first time to meet each other and to pay tribute to the two men who had given them a future.
"We owe them everything," one father remarked.
There was a general air of nervous excitement as each family arrived.
As they made their way down the staircase to the blue painted reception room, there were a host of questions.
Who else would be here? Was it a complete surprise?
As they began to mix, it took no time at all for complete strangers to be transformed into instant best friends.
Watching from the sidelines, it was clear that each of them shared an unusual bond.
Gill Hayward and daughter Holly Reich had flown in from Texas; the Holtons and the Vardeys from Ireland. Others had come from other parts of the UK.
The twins came through surgery well
Holly was the eldest, having been Professor Spitz's first case, with fellow surgeon Mr Ed Kiely, nearly 20 years earlier.
It had been a journey into the unknown for the two men and sadly Holly's twin, Carly, had died.
Other more recent cases like the Rahman twins had been more successful.
Looking splendid in their bright pink identical dresses, the two year olds ran up and down the room laughing and playing.
It was an infectious warmth. And then the Prof and Mr Kiely arrived. It was a moment to remember.
Back in the hospital, Msendoo and Iveren were coming to the end of their ordeal.
The twins had been successfully separated in an eight hour operation with the Prof and Mr Kiely managing to divide the liver without too much loss of blood.
However, in the aftermath of the separation, Iveren had been on the critical list in intensive care. It had been a tense time for all concerned.
Holly Reich was separated from her twin by Professor Spitz and Mr Kiley
With expert care, she had pulled through, and both were now well enough to be going home to Nigeria.
I now understood something that I had just witnessed earlier at the hotel.
Both the Prof and Mr Kiely had played a life-changing role in these and hundreds of other children's lives.
Their walls were adorned with pictures of past patients and clearly they cared deeply about them. This was no ordinary surgical partnership.
But then another thought struck me. Like their conjoined patients, they were about to be separated as Spitz retired.
As Mr Kiely told me "I don't like to think about it too much, things will be very different. He's always been my phone-a-friend, and I've always been his."
Their lasting contribution is summed up by one of the parents: "They have almost became part of the family, like father-figures, holding our hands through the most difficult time of our lives.
"We now have two healthy, independent children who can live normal lives. What more could we ask for?"
Separating Twins is broadcast on BBC One on Monday 21 March at 21.00