More than 200 leaders have signed letter to address implications for industry following George Floyd's death.
Return will be voluntary and flexible.
Holding company has handed agencies more responsibility for creative standards.
WPP CEO is making redundancies but says China has shown recovery 'can be quick'.
WPP first quarter revenue down -3.3% as it implements more cost-cutting measures
A number of holding companies say they will not enter the awards, while others have yet to decide.
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