I’ve imagined many times how this meeting might go. I’m a stranger to Mariana and she could well reject me. But I underestimate Mariana. As I step from the truck she rushes towards me, arms outstretched and leaps into my arms. She hugs me and laughs, I hug her and cry. It’s a very emotional moment for me.

We’ve driven by truck across the city of Cartagena in Colombia, South America. I’m here to visit Mariana, a little girl of five years old, who lives in a very poor community 20km (12miles) outside of Cartagena along unmade roads and often rutted tracks. I’ve been sponsoring Mariana since she was a baby through Plan UK and I’m very excited at the prospect of meeting her for the first time.

Over the years I’ve collected photos of Mariana and letters which her mother has written to me (in Spanish and translated for me) and I reckon mum has been collecting my letters for Mariana. In her tiny house with earth floors her mum serves drinks and a big bowl of fruit which I’m duty bound to consume.

We then head off to Mariana’s school where her classmates and their parents are waiting to greet us. Her teacher gives us a slide show about Mariana, all the class sing a song, Mariana does an animated solo and it’s time to say goodbye. Mariana has given me an unforgettable experience.

She’s one of seven children – all girls – that I sponsor with Plan UK in different parts of the world. Thirty years ago I joined Plan and I have sponsored almost 30 children since then. With Plan you not only change the life of a needy child but also her family and her community. Your sponsorship goes towards clean water, schools, school meals, books, health education and clinics. It’s wraparound care and I like that. But mainly it’s about transforming children’s lives. Breaking the poverty cycle. Opening up their options, widening their horizons and giving them a chance for a better life.

Meeting Mariana, who told me with great self-confidence that she wanted to be a doctor, I realised her care has to be continuous. I have to be there for her for the long haul, even after I’m gone.

Mariana is my reason for being in Colombia but there’s much more I mean to see.

In Pozon, another very poor community near Cartagena, I visit a centre for teenage mums. None are over 18, the youngest is 16. They meet up for companionship but also for teaching on nutrition, ante-natal care, hygiene, home care, breastfeeding and baby care. They start the day with “Breakfast with Love” and are taught how to cook healthy meals in the kitchen.

UK teenage mothers could learn a lot from these mums. They’re industrious, expertly sewing baby clothes as we chat. They’re very good mothers and breastfeed their babies on demand throughout the morning. As a result the babies are contented and hardly cry.

After my meeting with Mariana the high spot of my visit to Colombia turns out to be a school in Camino De Luz another deprived community outside of Cartagena. This is a school with a difference because it provides wraparound care for pre-school children and it’s the brainchild of Plan. It’s a regular part of daily life to over 100 children coming from neighbouring communities. When we arrive playtime is in full swing and we’re greeted by crowds of joyous children clamouring for attention.

What this school does is a revelation. Lessons, it turns out, are remarkably similar to those my grandchildren have in the UK but there are some special elements. In one classroom children are having a lesson in self-expression and creativity – dancing, laughing, banging things together, singing and scampering about.

There’s a tiny library where children can go and “read” and there are two four-year-olds looking at books (one, Where the Wild Things Are!) when I go in. A great scheme has sprouted from this tiny library. It’s called the Moving Bag of Books. Each child takes home a bag of books for their parents to read and to look at together. (In Colombia homes don’t have books and parents don’t read to children.) The next morning the bag of books moves on to another child. Schools in the UK could well imitate this simple scheme.

The kids here are well nourished. They get three meals plus milk and fruit during the hours of 9am-3pm at school. They have to. There may be little food at home.

My trip ends with a glorious event in Bogota, a celebration of the United Nation’s first ever ‘Day of the Girl’ which is being marked all over the world. In London the Millennium Eye was pink for the whole day as were the pyramids in Egypt and the Empire State building in New York.

We are treated to a stunning concert by Ilona, the Rhianna of Colombia who’s joined on stage by girls from all over the country whom Plan has plucked from poverty and changed their lives through education. These girls are irresistible, full of spirit and hope. A ten-year-old tells the huge audience gathered to celebrate girls, that to her, respect feels like love. Any 10 year old in the UK would say the same.

I started my trip with Mariana, who is embarking on her transformational journey out of poverty. On the Day of the Girl I see Colombian girls transformed. I’ve come full circle.

To find out more about PLAN visit www.plan-uk.org or call 0300 777 9779.