I don't think it is being an "80's office worker" or even being slightly stuck up, though i do accept that what people wear in the South of France may be slightly different to the UK.
It is an interview so you dress up for it, rightly or wrongly for men that means a suit. I rarely where a suit for work but I would always wear one for interview, it shows you're making an effort, it shows you care about your appearance and it shows you respect the people interviewing you. You may not agree that this should be the case but unfortunately it is in most industries in the UK.
Think of it like this, I have never known anyone not get a job by wearing a suit, but i have known people not get a job by not wearing a suit.
But again, please don't wear brown shoes and black trousers, and please don't wear a shirt with a short sleeved shirt.