\section*{Acknowledgments}
I would like to give credit where credit is due: this work would not have been undertaken without the scientific vision of Alain Blondel, and his firm belief that the final state polarization would suffice to disentangle the tt$\gamma$ and ttZ couplings. 

A great deal of inspiration also came from the passionate debates about the merits of the FCC with my former thesis advisor and scientific mentor, Fran{\c c}ois Le Diberder, and my former lab director, Fran{\c c}ois Richard. I am grateful to both. 

I would like to sincerely thank Zenro Hioki for digging out his code written 15 years ago, running it for me, and allowing me, with his patient explanations, to understand why my uncertainties were so much smaller than those obtained in Ref.~\cite{Grzadkowski_2000}. 

Finally, I am indebted to Patrizia Azzi, Alain Blondel, Christophe Grojean, and Roberto Tenchini, for their careful reading of the manuscript and for the wisdom of their comments and suggestions. 