I've only read about 4/5 of this thread… it is getting long!
I'm surprised not to have seen mention that the title of 'Engineer' has a protected status in most European countries, but not in the UK.
In the UK if you consider yourself an engineer you can call yourself one, or it can be used in any job title that involves some form of engineering in the role.
In the UK we usually rely on fellowship membership of some other institution to supply post-nominal letters which serve a function of identifying professionals etc.
Note that " only fellowships of learned societies are listed, while fellowships and memberships may be listed for professional bodies " (Debrett's via Wikipedia).
Any profession can set up its own professional institute. An institute may receive a Royal Charter – this in itself does not confer chartered status on its members. I am a member of the Chartered Institute of Ecologists and Environmental Managers and my MIEEM became an MCIEEM when it got the charter. My chartered status though comes from the Society for the Environment, CEnv which acts as an 'umbrella' for numerous professional environmental institutes. Just like engineers, anyone can call themselves an environmentalist (even if they haven't got a beard and sandals) but you need a CEnv to be a Chartered Environmentalist.
So, in short, Chartered Engineers or members of engineering professional bodies use appropriate letters to show professional status rather than having 'engineer' in their job titles or as a post nominal (like the European 'Ing.'
Neil