Did Privatization esp of key transport and telecommunication infrastructure improve performance and welfare?

There is an assumption that privatization in 80s and 90s was a "good idea" (tm). That is, it improved efficieny, quality. That consumers got a better deal, more choice etc?

But is this true? Specifically:

• Did privatization increase welfare?
• How did privatized companies compare to ones that remain nationalised over the same time period?
• Did competition really happen? (Or did we just regulated private monopolies)
  • Is it worth distinguishing simple transfer to private ownership to competition claims?
• Did competition work?
  • How much competition is there in e.g. telcos?

Take example of UK where most of transport infrastructure is now owned by foreign governments national transport companies (Is deutsche bahn privatised or RATP?