People with disabilities are being excluded from international development work across the world.
I can say that with confidence - or at least, I think I can.
The reality is that the picture is unclear because no one bothers to count the number of children with disabilities in school or the percentage of women with disabilities accessing support for domestic violence.
That's even though we know children with disabilities are far less likely to attend or complete primary school and women with disabilities are far more likely to suffer from violence.
Why is this a problem? Whilst data remains weak, we do know the scale of the issue. The first World Disability Report found in 2011 that people with disabilities are likely to make up at least 15 per cent of the poorest communities on the planet. Yet there is not one mention of people with disabilities in the Millennium Development Goals, one of, if not the, key international development framework.
In response, on 3 December, the International Day of Persons with Disabilities, Sightsavers launches its first ever UK campaign, Put Us in the Picture. We're calling on the UK Government to change the way it does international development.
We work with organisations across the world who represent people with disabilities. We have also recently undertaken research, using researchers with disabilities, and from the communities they are researching, to find out what people with disabilities think are the key issues for them. They tell us they are left out of employment, health and education services. But that just as importantly, they are unable to access their legal or civic rights and that they suffer from violence and discrimination.
There is sufficient evidence that in most sectors of social, economic or political development, people with disabilities are disproportionately marginalised.
Children with disabilities are more than twice as likely never to attend school; only 35 per cent of working age adults with disability in the US are working, and under-five mortality rates may be four times higher for children with disabilities in some countries.
The figures are open to dispute, because the available data is not strong enough. But they are as likely to show a worse picture as they are a better one.
What isn't in doubt is that people with disabilities are often among the poorest in their communities, and that the very development programmes designed to address poverty are leaving them behind and potentially even increasing the disparity between them and the rest of their communities.
Now is a great time for change. With the development sector working together to agree the new goals to end poverty beyond 2015, there is a once in a generation opportunity to redress the balance and make sure people with disabilities participate in, and benefit from, development programmes.
The disability movement's slogan is "nothing about us, without us". It's a good call because it captures the shocking lack of consultation and representation afforded to disabled people in every aspect of life.
But maybe now the time has come to say "nothing, without us" and to recognise that with one billion people on the planet estimated to have a disability, no international development programme can call itself effective unless it specifically addresses the issue of disability. Much as we would expect with gender.
Along with our disabled people's organisation partners and the people with disabilities they represent across the world, Sightsavers is calling on the UK government to follow its own stated position on "leaving no-one behind" and to lead the way by putting disability at the heart of UK international development policy.
People with disabilities have long been out of the frame. It's time to recognise that without actively including them, international development policy will continue to be just a sketch, not the full picture.