Southill is a small, quiet village built around its historic estate, and that combination — small population, private landmark — makes for a slightly different local search picture than most of its neighbours.
Southill Park, the Georgian estate the village is named after, has been in the same family for generations and isn't really a public visitor attraction in the way Old Warden or Moggerhanger's landmarks are — so unlike those villages, there's no meaningful "near Southill Park" search traffic to try and capture. It's worth knowing that distinction, because chasing the wrong kind of local search wastes effort that could go somewhere more useful.
What Southill does have is proximity — a short hop from both Biggleswade and Shefford, in a stretch of Bedfordshire where a lot of search volume for smaller villages effectively gets absorbed into the nearest town's name. For a business based here, that means the practical move is setting your Google Business Profile's service area to genuinely reflect Biggleswade and Shefford alongside Southill itself, since that's where the actual people searching for what you do are typing their query.
Beyond that, it's the same fundamentals as everywhere else on this list: a properly filled-in listing, current reviews, and a website that doesn't assume everyone already knows where Southill is.