I went to a business breakfast wearing a black suit (jacket + trousers), paired with a burgundy shirt underneath and a pair of box fresh New Balance 327, white and burgundy. I had to travel by car and by train to get there and walk 20 minutes in the City, so I went for smart casual. DH is saying the sneakers look odd but I am pretty sure it is acceptable these days to wear them ironically under a suit? For reference, I work in the charity sector but it was a business event.