The price is right ?

The BBC decided Ripper Street had run its course when series 2 finished with an average audience of around 4.8m.

Interest was re-kindled when Amazon stepped in to fund/co-fund series 3.  On Friday night series 3 ended with 2.19m viewers on BBC1 - 9.5% of the available audience.  This puts the average overnight audience for the series under 3m, and perhaps around 4m with catch-up.