The court has to examine 'harm' and 'culpability' and to decide whether they're 'high' or 'low'.
'Harm' will be high if the level of injuries were particularly high (e.g. life-threatening or resulting in serious permanent disability or scarring).
'Culpability' will be high if, for example, the offender deliberately sought out his victim or operated as part of a gang.
If both harm and culpability are high the judge must work within a sentencing range of 9 to 16 years, with a third knocked off for an early guilty plea. (i.e. the sentence would be between 6 years and 10 years 8 months)
If one of the factors is high, but the other isn't, the sentencing range is 5 to 9 years, less one third. (i.e. 3 years 4 months to 6 years).
If both harm & culpability are low the range is 3 years to 5 years, less one third (i.e. 2 years to 3 years 4 months).
The time actually spent 'inside' is usually half of the nominal sentence (but, for sentences of 4 years upwards, it can be up to two thirds of the sentence passed by the judge). So the shortest time that your mate is likely to actually be in prison is one year.
Sourced from here:
http://sentencingcoun...ine_-_Crown_Court.pdf
Chris