LONDON BRIEFING:ANOTHER WEEK, another shareholder showdown, and tomorrow it's the turn of unhappy investors in insurance group Aviva to take their board to task.

The venue switches from the Royal Festival Hall on the South Bank – scene of last week’s stormy Barclays meeting – to another concert venue, the Barbican, in the heart of the Square Mile, and boardroom excess will again be top of the agenda.

Like Barclays, Aviva has been forced into making 11th-hour concessions on pay in an attempt to head off an embarrassing public revolt, but that is unlikely to appease shareholders when they meet. At issue is the remuneration of chief executive Andrew Moss, who enjoyed a £5 million pay and perks package last year despite the rather less than impressive performance by the insurance group.

Institutional investors are also unhappy with the £2.5 million “golden hello” awarded to the head of its UK business, Trevor Matthews. He joined Aviva last year and his welcome package included a cash payment of £470,000 to compensate him for giving up unvested shares and his 2011 bonus from his previous employer.

On Monday, realising the depth of shareholder disapproval, the Aviva chief executive waived the 4.8 per cent increase that would have taken his basic salary above £1 million. Aviva’s remuneration committee admitted it hadn’t handled things as well as it should and insisted it takes the views of its shareholders seriously, promising to review its pay policies.

Despite that, it defended its decisions on pay for last year, saying the sums awarded were “appropriate reward” for the group’s operating performance and strategic progress last year.

That will be for shareholders to decide, however, and the board will certainly be subjected to some uncomfortable questions at the meeting.

Aviva is not the only major company facing criticism tomorrow. Shareholders in pharmaceuticals giant GlaxoSmithKline gather for their meeting in the afternoon and are being urged by the investor advisory group Pirc to challenge its remuneration policies, which it believes are not stretching enough.

Pirc highlights what it warns could be excessive payouts in the future, particularly for GSK chief executive Andrew Witty, who is entitled to earn 600 per cent of his £1 million a year base salary under long-term incentive schemes. Shareholders are likely to go easier on GSK, however, as its performance – despite a hiccup over the first quarter this year – has been far superior to that of the insurer. The Aviva share price has slumped by 30 per cent over the past year.

This new wave of shareholder activism sweeping the City has taken companies such as Aviva and Barclays by surprise, as demonstrated by their last-minute attempts to head off revolt by tweaking aspects of executive remuneration.

It didn’t do much good at Barclays – chief executive Bob Diamond’s concession to submit half his £2.7 million bonus to more demanding targets was not enough to prevent the group being dealt a bloody nose by shareholders last week, when 31.5 per cent refused to back the bank’s remuneration report. And more than one in five investors failed to back the re-election of Alison Carnwath, the non-executive director who heads Barclays’s remuneration committee.

Other high-paying companies in the line of fire include Trinity Mirror, where shareholders are to gather for their annual meeting a week tomorrow at the Hilton Hotel in Canary Wharf, the Docklands financial district. The newspaper group has already made concessions on the lavish rewards earned by chief executive Sly Bailey and other top executives but a number of shareholders feel they have not gone far enough, given the poor performance of the group.

When Bailey took over in 2003, Trinity Mirror was capitalised at £1.1 billion and its shares trading at 390p. Now it’s worth a mere £80 million and its shares worth little more than 30p.

Yet the chief executive was rewarded with a £1.3 million pay package last year.

Another company in the shareholder activists’ sights is Sir Martin Sorrell’s advertising empire, WPP. Sorrell, who received a near-£13 million pay package last year, has been awarded a 30 per cent increase in his base salary, to £1.3 million, and his potential bonus payments have been doubled.

The WPP board may feel it has already bowed to shareholder concerns; after all, it had originally proposed a 50 per cent salary increase for the chief executive. Shareholders will get the chance to give their views next month – and they can do so in Dublin, as the annual meeting is being held on June 13th at the Convention Centre, North Wall Quay. A date for the diary.

Fiona Walsh writes for the Guardian newspaper in London