The job title "Engineer" is protected in the United Kingdom. That is to say, you can't just call yourself an engineer - you have to be qualified to be one!
For example, a recognised time-served apprentice or an engineering degree will allow you to use the title legally.
That is why the railway have "fitters" or "rolling stock technicians", legally they cannot be called engineers because of there qualification type.
Engineer is NOT protected in the UK
also a time served apprentice is NOT an engineer by the definitions used by the EngC
a time-served apprentice May be eligible to apply for recognition as a Engineering Technician especially if they have done level 4 or even 5 quals
Professional Engineers have academic knowledge equal to NQF5 ,6 or 7
Incorporated is generally HND or BEng for academic exemption, and BEng and additional study or MEng is needed for academic exemption for Chartered .
as others have said there is a possibilty for action against someone who claimes to be an Eng Tech / Ieng or Ceng without actually holding the accreditation - but unlike impersonating a Lawyer or health professional this is all within the civil law and there's no 'licence to practice' for engineers in the UK (in general - there are specific things but equally you don;t have to have Eg C to do the qualification) where as a lawyer or health professional can;t practice without their registration and are legally prevented from legitimately doing certain things that are integral to practice.