The most vocal of the opponents to Owen Smith being removed from his position also happen to be Labour Plotters:
Chuka Umunna, Anna Turley.
You can find them listed here (Along with Owen Smith): https://bit.ly/2pAA3L7
And of course, what Labour Plotters do was exposed in the blockbuster revelations, The Lobby, 4 part YouTube.
Photo from https://commons.wikimedia.org author: exadverso Creative Commons Attribution 4.0 International license