The Public Health Responsibility Deal (RD) is a public-private partnership in England involving voluntary pledges between government, and business and other public organizations to improve public health. One such voluntary pledge refers to the reduction of trans fatty acids (TFAs) in the food supply in England by either pledging not to use artificial TFAs or pledging artificial TFA removal. This paper evaluates the RD's effectiveness at encouraging signatory organizations to remove artificially produced TFAs from their products. We analysed publically available data submitted by RD signatory organizations. We analysed their plans and progress towards achieving the TFAs pledge, comparing 2015 progress reports against their delivery plans. We also assessed the extent to which TFAs reductions beyond pre-2011 levels could be attributed to the RD. Voluntary reformulation via the RD has had limited added value, because the first part of the trans fat pledge simply requires organizations to confirm that they do not use TFAs and the second part, that has the potential to reduce use, has failed to attract the participation of food producers, particularly those producing fast foods and takeaways, where most remaining use of artificial TFAs is located. The contribution of the RD TFAs pledges in reducing artificial TFAs from England's food supply beyond pre-2011 levels appears to be negligible. This research has wider implications for the growing international evidence base voluntary food policy, and offers insights for other countries currently undertaking work to remove TFAs from their food supply.