So, how much time are they likely to serve? As all the crimes that they've been convicted off relate to the same event, I would expect the sentences to run concurrently. How much time they serve will then depend on the sentence for the most serious offence, which is manslaughter. These are the sentencing guidelines for gross negligence manslaughter. If the judge thinks there is high culpability, then the starting point is 8 years. With very high culpability, it's 12 years.
From there, the judge then adds time or takes it away based on aggravating or mitigating factors. Gordon is likely to do worse than Marten here owing to his previous convictions.
With high culpability, I reckon they're looking at somewhere around 10 years, and with very high, around 14 years.
We need to bear in mind that they would ordinarily be released on license after half their sentence, and that the time they've spent on remand will count towards the time they serve.
www.sentencingcouncil.org.uk