Hey Memo! I can't comment specifically on engineering, but my supervisor did her PhD at the Open University (after doing undergrad and masters degrees at UCL and Cambridge) and she is one of the world leaders at what she does (clinical psychology), so it certainly hasn't held her back! I think the main thing for the PhD is to get the topic right and work with supervisors who have similar interests and will be able to support you well- the institution is less important for the PhD than for undergrad/masters degrees. Best, KB