Teggiden will join the management team of Rob Porteous and Dave Askwith, who are also creative directors.
D&G is in the process of growing its London office to rival its counterpart in LA, which currently employs 145 people.
Treggiden comes from Kindred agency where she spent four years in client services on brands including Kia, Blistex, The Children's Mutual and LA Fitness.
Previously Treggiden worked at agencies Chemistry, Meteorite and Wunderman on clients ranging from Quality Street to English Heritage.
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