Forster will be working to review brand, strapline and creative identity.
ActionAid was awarded the prize for the world's most innovative fundraising campaign at the Global Fundraising Awards held in the Netherlands last week.
The development charity picked up the award for its Yorkshire Means the World campaign, which was launched in October 2009 when the UK was still in recession.
Audience communications, part of the M&C Saatchi Group of companies, has hired Rosie Strachan as account director. She was formerly an associate director at Fishburn Hedges.
True Volunteer Foundation has called on charities to 'step up and identify' how the impact of the public spending cuts can be minimised. In a statement, TVF partnerships team member Kim Momtaz said: 'There is no doubt there are thousands of charities delivering vital services. Some of these services will cease to exist without national or local government funding.'