An architectural aficionado, Prince Charles is was hosting the 150th anniversary of the Royal Institute of British Architects. During this occasion he described the proposed extension to the National Gallery by Ahrends Burton Koralek as "a monstrous carbuncle on the face of a much-loved and elegant friend." Because of his influence the design was abandoned and a historicising design was built instead. By intervening, Prince Charles spawned a new, derisory language of popular architectural criticism. Discussions of new buildings published in newspapers are now full of words like "carbuncle", "monstrosity" and "eyesore".
Prince Charles is not an architect and has not studied architectural history. However, he has privileged access to the media, more so than any architect or architectural body. In 1984 he presented A Vision of Britain and published a spin-off book of the same name, with which he was able to sway public opinion. His tastes are very conservative and he seems to habitually value buildings in historic styles. In particular he spoke out against 60s Brutalism.
This is a quote from the series:
For far too long it seems to me, some planners and architects have consistently ignored the feelings and wishes of the mass of ordinary people in this country ... To be concerned about the way people live, about the environment they inhabit and the kind of community that is created by that environment, should surely be one of the prime requirements of a really good architect.
Through these channels he was able to promote a tepid kind of neo-Georgian by architects like Quinlan Terry. They were acutely Thatcherite, most of them being country houses or city office buildings. They were designed in the 1980s, but it could be two hundred years earlier. So they are aesthetically and politically reactionary, but they're inoffensive to the public, who often conflate old buildings and old styles with good architecture.
Prince Charles's opinions were ridiculed by RIBA, but found favor with the public. Whatever you think of him, he did highlight the conflict between those prescribing architecture (specialist architects and critics) and those who generally have to live with it, the public. After all, shouldn't architects give the public what they want?