Those who call for international aid to be scrapped are not considering that benefits it brings to the UK.
UK aid is not simply a charitable act or the right thing to do. The UK aid donation helps increase British influence overseas, (and helps underpin national security).
In 2015 there was a Treasury Policy Paper 'UK aid: tackling global challenges in the national interest'. It said that ‘UK leadership in [tackling poverty] will cement our global moral leadership, and make a strong contribution to the UK’s soft power and our ability to project our influence across the globe.’
The UK will also be able to build new trading relationships and even ensure that the issues it prioritises are discussed and accepted across the developing world, all aided by Britain’s development aid agenda.
Softy diplomacy is a huge benefit to the country as well as influence. The problem is - it's an intangible. Because we can't see the immediate benefit, some people think it doesn't exist.