The group, a holding company for the property investment business of the family of Earl Cadogan, is splitting with decade-long incumbent Halpern as part of the review.
Halpern has declined to repitch for the work. MD Jennifer Burner told PRWeek: "We have loved working with Cadogan Estates for the past ten years and are very proud of the work we have produced together, including the very successful Chelsea in Bloom. While we have declined the opportunity to be part of the pitch process this time, we wish the brand every success in the next phase of its brand development."
The estate has been under the ownership of the Cadogan family, among the richest in the country, for more than three centuries.
Of working with Halpern, Cadogan CEO Hugh Seaborn said: "We have valued our relationship over the past decade, working together to evolve the Duke of York Square positioning, and are grateful for all their support."