Where under an instrument other than a will coming into operation after the commencement of the Conveyancing (Amendment) Act 1930 property stands limited to a person for a contingent or future interest, or stands limited to trustees upon trust for a person whose interest is contingent or executory, such interest shall, subject to the statutory provisions relating to accumulations, carry the intermediate income of that property from the time when the instrument comes into operation, except so far as such income or any part thereof may be otherwise expressly disposed of.