11. (1) If any property is subject to a trust other than a trust which the Official Trustee is prohibited from accepting under the provisions of this Act, and all the trustees of the surviving or continuing trustee or trustees and all persons beneficially interested in the trusts are desirous that the Official Trustee shall be appointed in the room of such trustee or trustees, it shall be lawful for such trustee or trustees, by an instrument in writing to appoint the Official Trustee by that name or any other sufficient description with his consent to be the trustee of such property:Provided that the consent of the Official Trustee shall be recited in the said instrument and that such instrument shall be duly executed by him.(2) Upon such appointment such property shall vest in the Official Trustee and shall be held by him upon the same trusts as the same was held previously to such appointment, and the previous trustee or trustees shall be exempt from all liability as trustees of such property save in respect of acts done before the date of such appointment.