Her new job means a move from Added Value, the WPP market research division she was the global chief executive of, to Grey, which was bought by WPP earlier this year.
The switch also allows the former Saatchi & Saatchi chief to renew her relationship with Procter & Gamble, one of Grey's bedrock clients.
Part of her role will be to oversee Team P&G, which co-ordinates the WPP companies servicing the world's biggest advertiser in the UK. She will also bring her experience to bear on getting more business into Grey London.
Grey declared its intention to hire a UK group chairman soon after Garry Lace's abrupt resignation as Grey London's chief executive last year. However, the appointment was delayed when Grey Global Group was put up for sale.
As the group chief executive, Ingram will also take responsibility for Joshua, Grey's integrated specialist, its PR agency GCI, the design agency Geometry and MDS Global Consulting, the data analyst.
Ingram, 44, built her reputation during 16 years at Saatchis. She left in 2001 to spend a less-than-happy few months as the chairman and chief executive of McCann Erickson UK.
Carolyn Carter, Grey's European president, claimed the appointment brought the UK group in line with Grey's other European operations and was not motivated by concern over a lack of top-level managerial experience at Grey London.
Ingram said: "Grey has fantastic clients and understands how to build brands."
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