Nine of the UK's 100 biggest listed companies were forced to issue clarifications to their boardroom pay plans before their annual meetings, as they attempted to avoid revolts by large City investors.

The companies – Aberdeen Asset Management, Compass, GlaxoSmithKline, HSBC, IMI, Imperial Tobacco, Pearson, Tui Travel and Unilever – all published updates on their remuneration policies to clarify how they intended to pay their top executives.

The list of statements, published on the website of the Investment Management Association, includes public clarifications issued by a total of 32 companies since a new vote on remuneration policies was introduced on 1 October last year. The IMA merged with the Association of British Insurers in June and this included the transfer of the ABI's institutional voting information service (IVIS), which publishes alerts on corporate governance issues at companies.

The annual general meeting season is drawing to a close and was the first in which investors received a vote on remuneration policies. These set the process by which a company intends to hand out bonuses over the next three years.

The clarifications issued by the FTSE 100 companies came because they were keen to avoid their remuneration policy being thrown out, since the vote is binding, unlike the existing separate vote on remuneration reports, which is merely advisory.

Andrew Ninian, the IMA director, said the clarification statements were a "good thing", adding: "It shows the process is working and shareholders and companies are working together."

Many of the clarifications involved the use of discretion of boards in setting bonuses, a feature of pay deals that makes shareholders uneasy, and were not all confrontational situations.

Outside the FTSE 100, the engineering company Kentz was the first company to have its policy voted down when 51% said no to the proposals at the annual meeting in May. According to the IMA's website, it did not issue a clarifying statement. One which did, the insurer Hiscox, still had a 42% vote against its remuneration policy but this was not enough to block it.

Some of the FTSE 100 companies which did issue statements still faced protests: about 20% of investors voted against the remuneration report of HSBC, for instance, as did 14% at Aberdeen Asset Management.

Companies do not need to put their remuneration policy to the vote next year – unless it was voted down during this season – and experts are still assessing the impact that it has had this year.

Sarah Wilson, the chief executive of advisory body Manifest, questioned whether the binding vote had been used by investors. She said that the shareholder spring in 2012 – before the policy vote was introduced and when a record number of remuneration reports were voted down – had been more important. Wilson pointed to data showing that pay awards for company bosses had fallen by 7% since 2012, following a 5% fall the previous year.

The FTSE 100 company to suffer one of the most bruising shareholder revolts this season was the upmarket fashion business Burberry, where almost 53% of investors voted against its remuneration report in protest against pay awards to its new boss, Christopher Bailey. Some 16% of investors voted against the remuneration policy, which is binding on the board.

One meeting still to come is at drinks company Diageo, which could face an investor rebellion on Thursday over its bonus payments to senior executives.