The statement indicates "The board of Directors shall be responsible for the implementation of this policy statement and shall provide adequate resources, training and investment to ensure compliance with the Modern Slavery Act 2015."

Although the company says "The board of Directors shall be responsible for the implementation of this policy statement and shall provide adequate resources, training and investment to ensure compliance with the Modern Slavery Act 2015," and there is a managing directors name at the bottom of the statement ("LM Porter, 
Managing Director"). It isn't merely enough to just state the managing directors title, there is no signature to show complete approval therefore, the answer to this question is the approval is not explicitly shown in the statement, but rather it could be argued there is some implicit approval.