Peach is a Joint as they come and very able, just like Nick Houghton. This is what the PM wants. George Z, whilst extremely capable, was probably seen as too partisan and too direct in his opinion. Whilst he and Pulford got on well and we did not see the internicene warfare of recent generations, Z still fought the RN (particularly the FAA) corner very hard, perhaps too hard at times. Z stood for grand strategy and as we know the Govt hate grand strategy.
As a side note. Tourist, you should step back a little from your pontificating - it is embarrassing.