Chartered London Teacher (CLT) status is a unique scheme designed by London Challenge to recognise and reward teachers' achievements and provide a framework for professional development. As well as having the prestige of being a Chartered London Teacher for life, educators receive a one-time payment of 1,000 British pounds from the school budget and Fellowship of the College of Teachers, the body that manages the registration and award process. CLT not only helps nurture and recognise teachers but it has the potential to change the culture of teaching and raise the bar of professionalism. The challenge is to scale up the impact on individuals and their pupils and so have a sustainable school, locality, and London-wide effect. The scaleable differences that CLT has the potential to make are described: (1) Developing more effective teachers; (2) Transferring knowledge; (3) Unifying London; (4) Raising the bar of professionalism; and (5) Helping recruit and retain high quality teachers.