After section 268 of the Sentencing Code insert -

"Serious terrorism sentence

268A. Serious terrorism sentence of detention in a young offender institution

A serious terrorism sentence of detention in a young offender institution is a sentence of detention in a young offender institution the term of which is equal to the aggregate of -

(a) the appropriate custodial term (see section 268C), and

(b) a further period (the "extension period") for which the offender is to be subject to a licence.

268B. Serious terrorism sentence of detention in a young offender institution: circumstances in which required

(1) Subsection (2) applies where a court is dealing with an offender for a serious terrorism offence (see section 306(2)) where -

(a) the offence was committed on or after the day on which section 4 of the Counter-Terrorism and Sentencing Act 2021 came into force,

(b) the offender was aged 18 or over when the offence was committed,

(c) the offender is aged under 21 when convicted of the offence,

(d) the court is of the opinion that there is a significant risk to members of the public of serious harm occasioned by the commission by the offender of further serious terrorism offences or other specified offences (see section 308),

(e) the court does not impose a sentence of custody for life, and