Shareholders were more likely to vote against pay reports at company annual meetings in 2012, but the trend has dropped off this year, according to a new study.
The TUC said its annual study of voting records of fund managers, pension funds and voting agencies showed there was a drop last year in support for remuneration.
Returns from 28 organisations revealed that the number supporting most pay reports fell from three in 2011 to just one last year.
But the union organisation said the number of reports on pay being voted down had fallen from six last year to three.
The report said there was a growing influence of overseas shareholders at AGMs, which the TUC believes will increase.
General Secretary Frances O'Grady said: "For corporate Britain to be more accountable, more needs to be known about the way investors vote. Shareholders need to be prepared to challenge proposals from the boardroom more frequently.
"Last year when company AGMs were feeling the heat of the shareholder spring, it looked as if investors were at last beginning to curb some of worst excesses of corporate Britain.
"But sadly 2013 has failed to live up to expectations. Only three reports have been voted down this year - and none of them were FTSE 100 companies.
"Shareholders who fail to make use of their voting and engagement rights fuel the argument for other stakeholders to play a role in corporate governance. If worker representatives were allowed to sit on boards, they could improve decision making provide an effective challenge to management."