In July 2018, Public Health England issued interim Recommendations on the treatment and prophylaxis of tetanus prone wounds and within the publication it said the document supersedes both the PHE guidance Tetanus: information for health professionals published in 2015, and the Green Book chapter 30 on tetanus. It now seems if it's more than 10 years since you had a tetanus toxoid vaccine and you sustain a tetanus prone injury you would now be given further vaccine and depending on the risk assessment of the wound, receive a dose to tetanus specific immunoglobulin as well. This is laid out in table 6 of the document.
I've explained this more fully in the Practice Nurse Travel Health Update for October 2018 - see the image below.
For more general information on tetanus see my FAQ page here.