A shareholder revolt is brewing at Thomas Cook after the travel agent proposed changes to its executive bonus scheme that could hand hundreds of thousands of pounds to top brass.Chief executive Manny Fontenla-Novoa is in line for an extra £200,000 if a decision to treat last year's volcanic ash incident as an exceptional event is rubber stamped.At Friday's annual meeting, chiefs will flag a change to its three-year incentive plan that began in 2007, basing bonuses on total shareholder return.The Association of British Insurers (ABI), Britain's biggest investor group, issued a 'red top' alert on hearing of the move that could hand Fontenla-Novoa stock worth over £450,000 compared with around £250,000 originally.Shareholders are angry as rivals haven't gone down the same route, while easyJet bosses have waived their 2010 payouts. It also comes just as Cook announced the political turmoil in Egypt and Tunisia will knock £20m from profits this quarter, disrupting what had been a good start to the year. Revenue in the first quarter rose by 7% to £1.81bn reflecting increased volumes and improved product mix, while the traditional seasonal loss fell to £37.3m.