Tesco suffered the biggest protest vote against a FTSE 100 company for more than a decade over proposed changes to its share option scheme at its AGM.

Forty-one percent of the votes recorded on the scheme at the annual meeting of Britain’s biggest retailer were against the proposed changed.

Manifest, a proxy voting agency, said the vote against Tesco’s option scheme was the biggest protest against such share schemes since it started monitoring voting in 1996.

The issue was not discussed at Tesco’s Glasgow annual meeting but Riskmetrics, the investor advisor service, had advised shareholders to oppose the changes, which extend to three years the one-year period in which leaving or retiring executives can exercise share options.

Lucy Neville-Rolfe, Tesco’s corporate and legal affairs director, said the company had done the right thing. The changes were backed by 55%, with a further 4% withholding their votes.

“We have shareholders [with options] right down to store managers in Tesco,” she told the Financial Times. “Because of the volatility of the markets, if they are retiring or retiring for ill-health reasons – or even if there is redundancy – it means they lose out in the current market because they only have one year to exercise the options.”

Tesco won the support of 89% of shareholders’ votes in rejecting a call by the Unite trade union for the retailer to improve conditions for agency workers – many of them migrants – at its UK and Irish meat suppliers.

Jack Dromey, deputy general secretary of Unite, said: “Others are moving. You are the biggest but you are the slowest. As market leader, you should lead and not lag.”

But Tesco chairman David Reid said: “We do not own or control these companies. Your desire to recruit in the meat industry is a matter for you.”