The slave trade was abolished for four good reasons including; slave rebellions, white middle class campaigners, working class campaigners and the Economy also had a big help to do with it.
Firstly the white working-class campaigners. A campaign began against black slavery in the towns. Petitions, as advertised on a banner for example, were popular ways of showing support, and attracted the working class. The banner would have been hung from a window or balcony to publicise the petition being circulated. In 1788 petitions began to flood into Parliament demanding the abolition of the slave trade. These petitions were from working-class people. In Manchester in 1788 over 10,000 working people signed a petition. Support grew: in 1792 over 20,00 Manchester people signed another petition (out of a population of 75,000). Huge meetings were held. .
I think the working-class campaigners had sympathy for the slaves because they had very many similar conditions to work in. For example hot sugar cane factories to work in similar to the cotton industry over in Britain, and the hard working labour in the fields to get the sugar similar to the farming in Britain.
I think the working-class campaigners were less important because of their power. The working-class pretty much "worked" so they were far less important than the rest of Britain unlike the middle class or the upper class who were more important and who had more of a say in things not just in this case but in many other things too including the general elections.
Overall I think the working-class campaigners didn't help as much as the middle class or the Economy to abolish the slave trade. But it did help and the government did realise the petitions, and the sympathy for the slaves that the working-class had for them. I did also think the government realised what little power the working-class had in these sort of thing and that did show how much they wanted that slave trade to be abolished.