Toscafund Asset Management LLP, which owns a 19.44 percent equity stake in the company, said Astrand had "failed to deliver" during his tenure and lacked the "appropriate track record or attitude" to oversee Speedy Hire's turnaround.

"We believe that it would be in shareholders' best interests if you were to resign ahead of the meeting to save both time and expense," Toscafund said in a letter to the chairman.

Astrand could not be immediately reached for comment.

Speedy Hire said it would hold a general meeting on Sept. 9 and post a full response to Toscafund on Aug. 12.

"We've always got other tools that can be brought to bear in the interest of shareholders but we can't speculate which route to take until we know what happens with the AGM," said Rod Barker, a partner at Toscafund.

Speedy Hire shares rose 2.2 percent to 35.25 pence after its statement on Wednesday.

The company has struggled since a botched implementation of an IT system last year. That and a shortage of equipment to rent out pushed Speedy Hire into a full-year loss and initiate a review of its operations.

Astrand had taken an executive role in July last year, when Chief Executive Mark Rogerson resigned after failing to turn the business around.

Toscafund called for Astrand's removal last month, saying the chairman had been "indecisive as a business leader" and that he failed to consult with shareholders regarding key board appointments.

(Reporting by Noor Zainab Hussain in Bengaluru and Maiya Keidan in London; Editing by Gopakumar Warrier and Anil D'Silva)