The difference between Colerne and Filton is not just any difference between the met at the two locations.
It is also a difference of the PAOM rules. Because Filton is so close to Bristol city and there is a carpet of ground lights all the way, then lower weather/vis limits can be used for night flying. Makes a big difference for jobs in the Bristol city area. Colerne is in a black hole on a hill.
Also the weather at Filton is VERY likely to be the same as the weather over Bristol city, so there is less uncertainty over go/no-go decisions.
Finally, the weather at Bristol Lulsgate airport has all sorts of reasons for being different from the weather in Bristol city area, despite being fairly close. There are major topographical features at Lulsgate tending to create poor vis, which do not apply in the same way at Filton or Bristol city.
Comparing the weather between Colerne/Lyneham and Lulsgate will tell you very little of interest: that could be the intention of course.