No, this is an out and out lie.
The government of the day does not and cannot interfere with "severe sentencing". It cannot. Sentencing is specifically controlled by the Judiciary. Current Sentencing Guidance is edited and amended ONLY by the Judiciary.
There are many examples where political pressure had a massive effect on sentencing.
Also he Home Sec sets guidelines for college of policing. The idea they are totally separate is naive and ignores a large amount of evidence.