The recent Global summit to end sexual violence in London was unique in its ambition; not only in efforts to bring sexual violence in conflict to an end, but also in attempting to engage the public in a challenging issue about which they had little prior knowledge and mostly no personal experience or connection. The public came to learn about the impact of sexual violence in conflict, and the work that's being done to stop it; as survivors conveyed their stories, there was a powerful sense that together, people from around the world were standing up against the perpetrators of these crimes.

As the UK manager of a global campaign for girls' rights, Because I am a Girl, understanding and fostering this sense of solidarity is important. I've become keenly aware of this as we re-launch our campaign this month, opening with a focus on violence against women and girls and, in particular, female genital mutilation (FGM).

FGM is an issue that provokes strong reactions; the appearance of an 'us and them' mentality is a risk. People from communities affected by FGM may feel that other aspects of their culture are being challenged or degraded while those in unaffected communities may take FGM as evidence of 'alien' values, feeding negative stereotyping.

For Plan UK, that's why it's all the more important that we treat FGM as we do any other human rights violation. It should be stopped, and everybody – every girl, woman, boy and man in every part of the world – can play a part in making that happen.

No-one would disagree that the movement to end FGM should be led from within the 29 countries in which the majority of cases occur. Our focus is always to support the work of local communities in identifying the underlying social norms that underpin FGM and challenging their persistence. But we should be clear that this doesn't – or shouldn't – mean that people in other parts of the world can't add their support.

An effective campaign gives a voice to those affected by a problem and then encourages others to amplify that voice. It recognises that rights are invalid if they are not respected universally and fought for across communities, cultures and continents.

A useful comparison here is campaigning on child marriage. Like FGM, this is an issue that does affect people in the UK, but that does not pervade society in the same way as it does elsewhere in the world. Child marriage will only be brought to an end by campaigns driven from within the countries of prevalence. But through our Take the Vow campaign, which ran in 2011, we asked the British public to declare their opposition to this practice on social media. This achieved two things: first, we showed that people can and should care about things that don't directly affect them or even their community. Second, it was made clear to decision-makers in the UK that this was an issue on which voters wanted action.

Rather than, as some might argue, undermining the indigenous campaigns, these activities helped place the issue on the agenda. The UK's Department for International Development took more notice of child marriage when it saw that people in the UK cared.

The sensitivities around FGM make the public discussion more charged, but the same logic applies to this issue as to child marriage. The UK public shouldn't be afraid to raise its voice. Longstanding campaigners on the issue, both in the UK and the global south, can draw strength from this support.

With this summer's #FGMRose campaign, we created a short, shareable video, supporting a burst of social media activity with deliveries of roses to people who could influence change and handouts to the public in central London. The rose motif is shocking without being graphic or offensive. It has provoked strong reactions, and very often from people who had never before considered what FGM was or how damaging a practice it is. Our aim was for the UK public to think differently about FGM and therefore not be put off campaigning about it, fearing it is some sort of 'niche issue' that's best avoided. It's now our most viewed video on YouTube by some distance.

At next week's Girl Summit, David Cameron will seek to galvanise global action to end FGM and child marriage in a generation. The UK public are showing they care - and the government knows it must respond. So when I'm asked, as I have been, "why should 'middle England' care about FGM?" my answer is clear: because it can make a difference in ending it.

Colin Walker is campaigns manager at Plan UK. Follow @colinwalkerplan on Twitter.

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