Prior to NPAS, the 43 English/Welsh Police Forces operated between them 33 helicopters and the odd fixed wing. Total cost to those Forces was approximately £46M. In 2017/8, those Forces paid NPAS £38.3M, so, a saving of £12M. However....
Prior to NPAS the various Units around the country flew approximately 24,000 hours. That equals £1900 per hour. In 2017/18, the remaining 15 NPAS helicopters flew 15,432 hours. That equals £2483.
So, savings, yes. Value for money, no.