After BMW sold MG Rover group for 10 GBP in May 2000, the new owner decided to use the Rover 75 as a platform for an upscale, sportier model, and thus the MG ZT was born.

It wasn’t just a trim level for the 75 but differed in many ways from its sibling. Phoenix Consortium, the company that acquired MG Rover, thought that the sporty brand deserved more than just a different label on the trunk and new bumpers.
https://www.autoevolution.com/cars/mg-zt-2001.html#aeng_mg-zt-2001-18i-16v-5at-120-hp