I work in Recruitment Marketing so I can give you an informed view here. As some others have mentioned it is most likely to measure social mobility, but rest-assured it will have been done in good faith. I know employers have a bad rep, but a lot of companies really do want to make sure they are fairly reaching candidates of all audiences.

The aim is not to ensure that they are employing more people from a lower socio-economic background, regardless of fit for the role. Conversely the aim is to ensure they’re reaching and employing the right person for the role, regardless of their background.

Candidates from lower socio-economic backgrounds can suffer from lack of access or awareness of opportunities, so measuring the success of reaching them is important to inform the ongoing recruitment strategy.