On route to developing zero carbon emission commercial electrical power generation, Tokamak Energy (TE) is developing Spherical Tokamak (ST) technology.  A key enabling technology for ST machines is the development of HTS magnets.  TE has embarked on a program of developing HTS magnets based on REBCO coated conductors for ST’s up to fusion reactor scale magnet sets.  This presentation will summarise the challenges and the progress of that program to date.