With regard to NJ's suggested way of doing the sums:
Let's consider a hypothetical medical student who has always been the star performer in his year group and who everybody sees as extremely likely to reach consultant level in almost record time. However, just before taking his final exams, he's arrested for (and subsequently convicted of) an extremely serious offence (e.g. murder) that he didn't commit. He's in prison for 20 years before it's recognised that a miscarriage of justice has occurred and he's then released.
He will have lost several year's earnings as a junior doctor, several year's more as a registrar and perhaps a decade's earnings as a consultant. He'll come out of prison without his degree and, having no job experience in any field, will probably struggle to find any type of work (and certainly not any with anything like a consultant's salary), meaning that he'll continue to suffer loss of earnings until he retires. He'll then suffer further loss of income, through not having a consultant's pension, until the day he dies.
NJ would have the assessment of his loss of earnings assessed upon his income when he was arrested and brought before the courts which, as he was then a student, would be NIL.
I humbly suggest, M'lud, that such a way of doing things would clearly turn a justice system into an injustice system.