tldr: Crime is great fun, but doesn't pay that well, especially at the beginning.
I'd say London salaries for publicly funded (legal aid) criminal defence are around:
£13-15k for a Paralegal
£15-20k for a trainee lawyer
£25-45k for a duty solicitor
£30-65k for a duty solicitor with higher rights (solicitor advocate)
You can find the salaries for CPS lawyers easily enough but IIRC they're around:
£30-40k for a crown prosecutor
£40-50k for a senior crown prosecutor
£50-70k for a crown advocate/manager/specialist prosecutor
Business crime/white collar crime & regulatory defence work is really the only way to get beyond £70k and into the six figures, but you have to be pretty smart and have a stroke of luck or two to get into those kind of roles, because there just aren't that many of them. Other than that you'd have to be a partner in a legal aid firm, or stay at the CPS for a long time and start to get into people management rather than legal work.
A young junior barrister will get from £50-£100 for a simple hearing and £80-£150 for a magistrates' court trial, and that's before tax and rent you pay to chambers so I'm not surprised some people would be better off at McD. Again, there are statistics around, but it wouldn't surprise me if some juniors starting out in crime or doing their second six pupillage would make about £15k-25k to start with. If they weren't earning £30k after a year or so (in London) and £50k after 5 years or so they'd be doing pretty badly. But it's also harder to become a criminal barrister than a criminal solicitor because there are fewer opportunities for pupillage.