Ruby and Rosie were born conjoined at the abdomen (Image: Adam Gerrard / Daily Mirror)

Looking from one incubator to the other, Angela Formosa gazed at her tiny twin girls in disbelief.

It seems such a simple thing, but for Ruby and Rosie, just being in their own separate incubators was nothing short of extraordinary.

For just 24 hours earlier the girls had been born conjoined at the abdomen.

Sharing part of the intestine and bowel, doctors decided to do the risky separation surgery immediately.

Angela and husband Daniel could only wait as surgeons separated the girls in a five-hour operation. Their chance of survival was just 25%.

But, against the odds, the surgery was a success.

 While at her 16-week scan, Angela got the news that her twins mightn't survive (Image: Adam Gerrard / Daily Mirror)

Recalling how they first saw the twins after the surgery in July, 2012, Angela says: “We were just sat in the middle of both cots, looking from one to the other.”

Angela, 38, is one of the few people who can begin to understand how mum Zainab Bibi must have felt this week when her twin girls finally left hospital.

Zainab’s two-year-old daughters Safa and Marwa Ullah, who were born conjoined at the head, were successfully separated by surgeons at Great Ormond Street Hospital in London.

Angela says: “Seeing another family go through this makes me feel happy for them that both their girls made it.

“There are so many conjoined twins where one or neither of the babies make it, so I feel such joy for them.”

 But the surgery to seperate the girls was successful (Image: Adam Gerrard / Daily Mirror)

Now, sitting in her garden in Bexleyheath, South East London, watching Ruby and Rosie playing on swings on the climbing frame, Angela is in no doubt about how far they have come.

Or how differently things could have gone.

Conjoined twins are rare, accounting for one in every 2.5 million births worldwide.

Half are stillborn and of those who do survive, 35% live for only one day.

 The operation lasted five hours (Image: Adam Gerrard / Daily Mirror)

Great Ormond Street Hospital has successfully treated more conjoined twins than any other hospital in the world and expect to see three sets a year.

The moment Angela was told she was expecting conjoined twins at her 16-week scan is seared in her memory.

She says: “I was numb. I just thought, ‘Why me? Why’s this happening to me? What have I done to deserve this?’

“It’s supposed to be the happiest time of your life and I was being told they’re probably not going to survive the birth.”

 After the operation they had to stay in the hospital for a further three weeks (Image: Adam Gerrard / Daily Mirror)

Angela searched the internet for answers and was devastated by what she found.

She says: “I was told not to Google anything, but it’s the first thing you do.

“It was scary, you see some terrible things, extreme cases.

“It’s just so rare, you never think it’s going to happen to you. I hadn’t even bought any baby things because we didn’t want to tempt fate.”

Angela gave birth by caesarean at University College Hospital in London on July 26, 2012, and remembers the moment she first saw her daughters.

 Angela is still amazed as she watches her girls achieve each milestone (Image: Adam Gerrard / Daily Mirror)

She says: “I just saw two perfect little girls wrapped in a blanket. Yes they were joined at the tummy, but they also had their arms, their legs, all their little fingers and toes.”

Soon after, they were rushed to Great Ormond Street.

She says: “They were in intensive care. The nurses put them in my arms. I got to hold them.

“It was really special. I went with them to theatre and off they went, through those doors.”

 Though seperated, Rubie and Rosie like to do things together (Image: Adam Gerrard / Daily Mirror)

When Angela read about Safa and Marwa it brought back painful memories. She says: “It reminded me of those times when my newborn babies were taken down to surgery at 24 hours old.

“As I was signing a consent form for their surgery, in my mind I was thinking, ‘Are they going to come back?’

“Like that mother [Zainab], I know what it feels like to think there’s a chance your babies won’t be coming back once the doctors open them up and started operating.”

 They at times sleep in the same bed (Image: Adam Gerrard / Daily Mirror)

Then came the longest wait of Angela and Daniel’s lives.

They sat in a family room, the opening ceremony of the Olympics on TV. Angela says: “I was just thinking anything could’ve happened.

“Something could’ve happened to one of them, or both.” Five hours later they got the call confirming their girls had come out of surgery.

Showing me a photo where she is holding her girls for the first time after their separation, she says: “It felt amazing to hold them both together, but separated.

“It was what I was waiting for. I was scared to hold them, scared I would drop them or hurt one, they were so tiny.”

 Angela asked the girls' school to keep them in the same class (Image: Adam Gerrard / Daily Mirror)

Angela, like Safa and Marwa’s mum Zainab, has nothing but total gratitude to the team of 15 doctors who saved her twins.

She says: “Without Great Ormond Street, I don’t know if they’d still be here. If we lived in a country where they don’t have advanced medicine they probably wouldn’t be here.”

Like Ruby and Rosie, Safa and Marwa will be in and out of hospital, possibly for the rest of their lives.

Angela says: “My advice to Zainab is to take each day as it comes and enjoy those precious moments. Every milestone is amazing.

“There were so many times I thought the day would never come – their first steps, their first day at school, our first holiday.

“I spend most of my time looking at them in amazement at how far they’ve come – how different it could have been if they could not have been separated.”

 Rubie and Rosie have an older sister, Lily (Image: Adam Gerrard / Daily Mirror)

When the twins were finally able to leave hospital almost three weeks after surgery, Angela knew they were happier together.

She says: “They were together in one Moses basket.

“I wanted to keep them together – they were more content. They’re still like that.

“This morning I went to wake them and they were in Ruby’s bed together.”

 The girls with Belle at Disneyland (Image: Adam Gerrard / Daily Mirror)

Ruby and Rosie will soon turn seven.

At the mention of their birthday, the girls bound over.

“We’ve already had our party,” says Ruby. “On my birthday I want to go to see Toy Story 4.”

Angela is open with the twins about their start in life, asking: “You know you were born joined together, don’t you?”

“Yeees!” Rosie says. “I said to my teacher, when we were learning about inspirational people, I said me and Ruby.”

“Because we’re special!” Ruby interrupts.

 Angela with her daughters (Image: Adam Gerrard / Daily Mirror)

Out playing with their protective 11-year-old sister Lily, the twins always stay close, holding hands.

Angela says: “When they were due to start school I told the head I didn’t want them separated because there was a point in their lives where you couldn’t physically separate them.

“They have been through so much. They have a special bond.”

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