Two months ago I completed the election data for the years 2009 to 2012, so that for every local government unit I already had at least one council term in my XML files. Two months later, I now finished another year, the elections taking place in 2009 and thus ending this year - another 3722 data points. I have already started the final complete list I found at the Election Commission with the elections which took place in 2004 and ending their term in 2008 - thus most of those which had their latest election last year. Those are another 3135 data points, but working through those may be a bit faster since back in 2008 there much less local administrations which had their mayor and council term out of sync.
I also found a source for the official election endorsements at the Election Commission, many PDF files which list the winning mayor and council candidates, both for the main election as well as for by-elections. Though only maybe half of the provinces are found in that collection, and it also just goes back till the spring of 2012, it also made it possible to add a lot of data to the XMLs.
Those sources combined made it possible to notice that the yearly tables for the Election Commission cannot be trusted fully - especially for the council sizes there are changes which cannot be explained. It seems that in the older table for several TAO simply the number of Muban in the Tambon was used to calculate the council size, ignoring the fact that some of the Muban may be completely within a municipality and thus not eligible to elect councilors to the TAO. But since Muban can also be shared between municipality and TAO, it may even be possible that the Muban area under jurisdiction of the TAO has no citizen. I now have 65 cases where the council seemed to have changed, but I could no verify whether it really changed or one of the numbers is simply wrong.
Finally, thanks to the online archive of the +Phuket Gazette, I was able to reconstruct the election history for this one province since the turn of the century, including the very interesting case of Pa Tong municipality which had three election within few months - the first and second election after its upgrade to a town in 2002 were nulled due to election fraud.
I have to hurry to work through the 2008 data, because soon the municipal upgrades will begin - with around 3249 TAO having either (or both) a mayor or council term end this year, several will get upgraded to municipalities. So far only few upgrades were decided and documented in the board meeting transcripts, but to be effective in September when most of the terms end I soon have to focus on those as well.