The grantor in any voluntary conveyance in which some future interest in real estate is conveyed or limited to a person not in esse may, at any time before he comes into being, revoke by deed such interest so conveyed or limited. This deed of revocation shall be registered as other deeds; and the grantor of like interest for a valuable consideration may, with the joinder of the person from whom the consideration moved, revoke said interest in like manner. The grantor, maker or trustor who has heretofore created or may hereafter create a voluntary trust estate in real or personal property for the use and benefit of himself or of any other person or persons in esse with a future contingent interest to some person or persons not in esse or not determined until the happening of a future event may at any time, prior to the happening of the contingency vesting the future estates, revoke the grant of the interest to such person or persons not in esse or not determined by a proper instrument to that effect; and the grantor of like interest for a valuable consideration may, with the joinder of the person from whom the consideration moved, revoke said interest in like manner: Provided, that in the event the instrument creating such estate has been recorded, then the deed of revocation of such estate shall be likewise recorded before it becomes effective: Provided, further, that this section shall not apply to any instrument hereafter executed creating such a future contingent interest when said instrument shall expressly state in effect that the grantor, maker, or trustor may not revoke such interest: Provided, further, that this section shall not apply to any instrument heretofore executed whether or not such instrument contains express provisions that it is irrevocable unless the grantor, maker, or trustor shall within six months after the effective date of this proviso either revoke such future interest, or file with the trustee an instrument stating or declaring that it is his intention to retain the power to revoke under this section: Provided, further, that in the event the instrument creating such estate has been recorded, then the revocation or declaration shall likewise be recorded before it becomes effective. (1893, c. 498; Rev., s. 1045; C.S., s. 996; 1929, c. 305; 1941, c. 264; 1943, c. 437.)