No there have been no alterations of the sort you mention s127 has received no amendments And just because an Act is 9 years old doesn t make it out of date Also the reduction for a guilty plea is not applied mathematically post sentencing See eg s174 2 d Criminal Justice Act 2003 The process begins with the court deciding the sentence that should be imposed for the offence s then selects the amount of the reduction by reference to the sliding scale then applies the reduction and finally pronounces sentence in court explaining what reductions were applied