(1)This section applies where—
(a)a sentence has been imposed on any person under section 225 or 227, and
(b)any previous conviction of his without which the court would not have been required to make the assumption mentioned in section 229(3) has been subsequently set aside on appeal.
(2)Notwithstanding anything in section 18 of the Criminal Appeal Act 1968 (c. 19), notice of appeal against the sentence may be given at any time within 28 days from the date on which the previous conviction was set aside.