"23. .... whereas an offender, the subject of an extended sentence, may not be released after serving half of the custodial term until the Parole Board is satisfied it is no longer necessary for the protection of the public to confine him, an offender serving a fixed term or determinate custodial sentence of 12 months or more will be released after serving half of his sentence (see section 244(3)(a)). It follows that if a consecutive determinate sentence is passed to an extended sentence it may be difficult to determine when the custodial element of the extended term ends and the determinate sentence begins. 24. In our judgment these difficulties do not arise if an extended sentence is made consecutive to a determinate sentence.... .... 27. .... the following points should be observed. First, consecutive extended sentences appear to provide considerable problems in determining the application of the appropriate licence period once the custodial element has been served. Secondly, similar problems will arise if a determinate sentence is made consecutive to an extended sentence. Accordingly we take the view that consecutive extended sentences and a determinate sentence consecutive to an extended sentence are, in general terms, not appropriate and should be avoided. However, we see no reason to suggest that such problems will arise if the extended sentence is made consecutive to the determinate sentence. 28. There is no reason to suppose that concurrent extended sentences raise any of the above problems, nor that an extended sentence concurrent with a determinate sentence will cause insuperable difficulties. ...."