Military Privatisation

Why is the Uk so keen to use PFI for services such as air refuelling and keen to privatise other services such as SAR while the majority of nations including bankrupt Portugal, Greece and Italy keep these services a military role
The French seemed to have rejected PFI or equivalent for the refuelling aircraft replacement
Canada has rejected the option of a privatised SAR service
The US seems to prefer the use of reservists to save money
Is the UK right to use privatisation to save money which to me seems a short term solution as I suspect these privatised services will be using many ex military personnel
thus avoiding many of the training costs?