I used to live round the corner from Square Mile’s previous roastery and what surprised me is that you could only ever really smell it in the immediate area. As in, right outside to the end of the street. I was a stone’s throw away but never once noticed it from my apartment in the two years I was there.
Blue circle is where I lived, red is where Square Mile were.
I also worked down the road from Ozone who managed to roast pretty large quantities regularly without any smell at all being noticeable outside.
I don’t know Brighton or that roaster but I can’t imagine they’re roasting larger quantities than Ozone or SM so presumably it’s only the very immediate neighbours who can smell it.