TI1 shareholders Global Value Fund, Invesco, Janus Henderson and Pelham, which together hold around 40% of shares in the trust, cite concerns about recent changes to TI1's strategy on the number and type of its investments, proposals to turn the trust into a special purpose acquisition company (SPAC) and about its share price performance.

"The TI1 Board is not fit for purpose," the rebel investors said in a letter to shareholders on Tuesday ahead of an extraordinary general meeting on Aug. 5 to vote on their resolutions to remove Sherwell as well as directors Anita Rival and Simon Holden.

TI1, which has previously recommended that shareholders vote against all the EGM resolutions, did not immediately respond to a request for comment.

TI1's investment management strategy is carried out by activist investor Nelson Peltz's Trian Fund Management, whose holdings include Unilever and Wendy's.

Changes to TI1's investment policy have impacted the timing and the extent of the value and returns that shareholders can expect, Glass Lewis said in a report dated July 20.

"We are generally sympathetic to the dissidents' argument that the investment manager and the board have taken actions that changed the fundamental nature and purpose of the company since most, if not all, of the company's major shareholders chose to invest in the company," Glass Lewis added.

TI1's board had made some efforts to address investor concerns, Glass Lewis said, and it recommended voting against removing the other two directors.

Fellow adviser ISS said in a July 22 report that it backed the removal of Rival, but was against sacking Sherwell.

Both advisers recommended adding the investors' choice of Robert Legget to the board.

(Reporting by Carolyn Cohn; Editing by Josie Kao)