The review concluded that it was not necessary to maintain trust offices in both Guernsey and Jersey, an Investec spokesman said.
The two islands, though separately governed entities, are only about 30km (20 mi) apart.
The spokesman said Investec’s other operations in Guernsey — banking and asset management — will not be affected by the "phased closure" of the trust office.
News of the planned closure was made public last week, when Investec Trust staff were also informed of the decision. Eleven were told they were losing their jobs immediately, and an additional 51 informed theirs would go eventually. The exact timing will be contingent on accommodating the wishes of the trust’s clients, the spokesman noted.
In addition to Jersey, Investec Trust Group also has offices in Mauritius, Geneva and South Africa, where its parent, Investec plc, is based. It’s chief executive, Xavier Isaac, is based in Geneva.