On page 4, it states that;

We will use the following key performance indicators (KPIs) to measure how effective we have been to ensure that slavery and human trafficking is not taking place in any part of our business or supply chains:

75% of existing sub-contractors and suppliers on our approved list to commit to our updated due diligence questionnaire confirming their compliance with our Anti-Slavery Policy

100% of new sub-contractors and core suppliers to confirm via our due diligence questionnaire that they will comply with our Anti-Slavery Policy

100% of new supplier and sub-contractor contracts to contain provisions requiring compliance with our Anti-Slavery Policy