.When the Official Trustee has by that name or any other sufficient description been appointed trustee under any Will, the executor of the Will of [the testator] [Substituted by Act 18 of 1919, Section 2 and Sch., for certain words.] or the administrator of his estate shall, after obtaining probate or letters of administration, notify in the prescribed manner the contents of such Will to such Official Trustee; and, if such Official Trustee consents to accept the trust, then upon the execution by such executor or administrator of an instrument in writing transferring the property subject to the trust to the Official Trustee, such property shall vest in such Official Trustee, and shall be held by him upon the trusts expressed in the said Will:

Provided that the consent of the Official Trustee shall be recited in the said instrument and that such instrument shall be duly executed by the Official Trustee.