It might have to do with the Stockton area having a larger population and a much larger area?
So less cases per person and less cases per area?
It's a bit daft though because they should just be treat as one, as so many people live in Stockton and work in Boro and visa versa.
It's like how in Boro (based on 1st to 7th October), Beechwood & James Cook has 7 cases, and Linthorpe East & Albert Park has 59 cases. They're treat the same (rightly so, as they're so close). Ingleby, Yarm, Stockton, Boro, South Boro etc, all need to be treat as one. They're too close, soo close where they can't not impact each other.
Ingleby West had 61 and Central Stockton, Portrack & Low Hartburn had 39, which is a lot, yet Thornaby and the bit in-between main Stockton, Ingleby and Boro, apparently doesn't have a lot.
There's no way on earth this lot of dark blue is not all intermixed/ intermixing with the light blue/ uncoloured:
https://www.arcgis.com/apps/webappviewer/index.html?id=47574f7a6e454dc6a42c5f6912ed7076