Anyone who has 40,000 Twitter followers, a book deal and known to millions around the country, yet is still in the middle of their A Levels is in a highly unusual position. Over the last year, Martha Collison's world has dramatically transformed after becoming one of the most loved contestants on the BBC's Great British Bake Off.

But before fame landed in her lap, Martha found herself outside the Tearfund tent at the 2014 Big Church Day Out. She should have been practising her bakes for the next recording of GBBO or even doing some exam revision, but she had already committed herself to volunteering at the event. As she watched Tom Herbert, one half of Channel 4's The Fabulous Baker Brothers, making doughnuts and recounting his trip to Laos to visit children at risk of trafficking, she thought, 'I could do this!' and subsequently got in touch with Tearfund. Today she is an ambassador for them and has just finished an epic 21 hour bakeathon to raise awareness and money for Tearfund's No Child Taken campaign.

I had the pleasure of spending a couple of hours with Martha during this marathon, talking about baking, life and her faith. It's anything but difficult to see why GBBO's producers chose her to be on the show when you experience her passion for baking first-hand. As we talked she spoke of how she prayed to God once she knew she would be on the show, asking for the opportunity to serve Him and do some good through it.

Martha's interest in combating trafficking and slavery had already grown through various church events prior to watching Tom Hebert's talk, which she now sees as a divinely appointed moment where she realised how her love for baking could be employed to positively impact the lives of others.Only months later as GBBO was being broadcast did she begin to appreciate just how much God would be able to work through her.

In February Martha travelled to Cambodia to see for herself both the consequences of trafficking and ways to prevent it. She described to me the upset of visiting a red light district and seeing girls her own age who had been lured away from their homes by traffickers and forced into a life of prostitution. However, she also experienced the joy of teaching other girls in different villages how to bake cakes with simple ingredients that they could then sell for a profit. When communities are educated about the way in which traffickers tempt people away from their homes with lies and false promises of jobs while at the same time being given ways of supporting themselves financially, then lives are saved from horrific suffering and misery.

As a result of her bakeathon, Martha has been able to spread this message thorough the media including BBC1's Breakfast. Thousands have listened to her telling the story of Nazeeb who was trafficked at 14 and made to work for 21 hours a day (hence the reason for the length of Martha's bake) in a zip factory. Eventually he was able to escape back to his home village. Since then one of Tearfund's partners has helped Nazeeb to set up a poultry farm which is allowing him to earn a living.

This Sunday (18 October) is also Anti-Slavery Day, which was established by our parliament in 2010 to remember those who are in slavery and being trafficked. The global scale of human trafficking is monumental and it is estimated that 1.2 million of those trafficked this year will be children. Children become particularly vulnerable to traffickers once their full-time education stops, which in poor communities is typically after primary school level.

Tearfund working through local partners and churches is seeing great success in combating this threat. As Martha saw in Cambodia, they are able to provide education, training in skills such as snack-making, hairdressing, motorbike repair and dressmaking, and starter kits to establish small businesses. This is an investment that has an immediate impact, but more importantly creates stability for the future.

When asking Martha about her own future, she replies that she is keen to continue to draw attention to this global epidemic and also see what she can do with her skills to help those in vulnerable situations closer to home. In all of this and as has been seen to date, she is not afraid to wear her faith on her sleeve and her confidence in God's love is infectious. Martha still sees herself as a pretty normal person who just happens to love baking, but she is also convinced that God can use the ordinary things in our lives to produce extraordinary outcomes if we give ourselves fully to Him. And based on what I've seen in her and in the lives of many others, including my own, I entirely agree.

You can donate to Martha's bakeathon via her JustGiving page.

Martha's Pistachio and Lime Courgette Cake

Ingredients:

250g courgettes

2 eggs

125ml vegetable oil

150g caster sugar

225g self-raising flour

1/2 tsp bicarbonate of soda

1/2 tsp baking powder

1 lime

For the icing:

60g pistachio nuts

100g cream cheese

150g icing sugar

Method:

1. Preheat the oven to 180°C/Gas 4. Grease a 'bundt' tin (i.e. a tin shaped like a ring) with butter. Make sure you get into all the corners or the cake will stick.

2. Rinse the courgettes and then grate (skin on) with the coarse side of a grater. (If it's too fine it will just turn into mush.)

3. Place eggs, oil, and sugar in a bowl, and beat until creamy. Fold in sifted flour, bicarbonate of soda, and baking powder. Stir in the courgette and half the grated zest of the lime.

4. Pour the mixture into the pre-prepared tin and bake for 30-35 minutes until golden on top and firm to touch. Remove from oven and leave to cool completely before assembling.

5. To make the icing, beat the cream cheese, icing sugar and juice of half a lime together until smooth. Spread on the top of the cold cake. Chop the pistachios and sprinkle them over the cake, then top with the remaining grated lime.