By Max Colchester 

Barclays PLC's new chairman, John McFarlane, Thursday vowed to speed up the U.K. bank's restructuring and improve returns.

Mr. McFarlane, who took over from outgoing chair David Walker, said the bank had to resolve a number of legal problems hanging over the lender and weed out unprofitable business units.

In a letter to shareholders he pledged a "dynamic" reallocation of resources at the bank.

"It is appropriate that we continue to evolve the strategy to fit the times and retain clarity on the proposition we are trying to build," he added.

Mr. McFarlane, who joined Barclays from insurer Aviva PLC, earned a reputation as a fearsome restructurer of struggling financial institutions. He has been on Barclays's board since January and has already performed a review of several business lines, according to people familiar with the matter. On Thursday at the bank's Annual General Meeting a shareholder asked how the directors would fare when "John McFarlane arrives with his big ax."

Problems related to past conduct continue to weigh on the bank. Earlier this year the bank put aside GBP1.25 billion ($1.34 billion) to cover potential settlements over allegations that it tried to rig foreign exchange markets. The provisions and restructuring costs pushed the bank to a full-year net loss in 2014. The lender recorded a negative return on equity for the period, a key measure of profitability. But in the last 12 months the bank's shares have rallied some 2.5% as investors bet that the restructuring will bear fruit.

Barclays Chief Executive Antony Jenkins said earlier this year that he felt justified in accepting a GBP1.1 million bonus for 2014 because of the progress the bank was making slimming down and refocusing on its retail and corporate business. The bank announces its first-quarter earnings next week. On Thursday Mr. Jenkins said that he was confident that 2015 would be a year of continued delivery of the strategy and that there would be more clarity on legal and regulatory issues. He added he expected "progress" on legacy issues in 2015.

At the annual general meeting Mr. Walker said progress had been made but "the journey is incomplete." He added that the criticism the bank has faced was "justified."

Write to Max Colchester at max.colchester@wsj.com

Access Investor Kit for Barclays Plc

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=GB0031348658

Access Investor Kit for Barclays Plc

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=US06738E2046

Subscribe to WSJ: http://online.wsj.com?mod=djnwires