7(1)
Where the Court of Appeal allow an appeal against conviction . . . and it appears to the Court that the interests of justice so require, they may order the appellant to be retried.
7(2)
A person shall not under this section be ordered to be retried for any offence other than—
(a) the offence of which he was convicted at the original trial and in respect of which his appeal is allowed as mentioned in subsection (1) above;
(b) an offence of which he could have been convicted at the original trial on an indictment for the first-mentioned offence; or
(c) an offence charged in an alternative count of the indictment in respect of which no verdict was given in consequence of his being convicted of the first-mentioned offence.