Ah, got to love this country, with it’s anachronistic customs…
Personally, I wouldn’t risk not wearing a suit, or at least a shirt, tie, jacket and smart trousers and shoes. It’s almost the law, really, for most jobs. The only interview I’ve ever gone for, casual, was for a retail position, and i’d already had a good chat with the boss, so virtually had the job anyway. Wore just a short-sleeved shirt, casual trousers and sandals. It was middle of summer, and 90+ degrees. The boss was wearing t-shirt, shorts and flip-flops! I think only in scorching heat, could you be excused a jacket, reallly.
Silly, though, isn’t it? that most people wouldn’tgive a toss whether you wore a ‘suit’ or not, yet it’s still not a good idea not to.
‘Making the effort’ is the key, really, and wearing the ‘uniform’ displays that.