You can do an portfolio search for councils by identifying council owned properties and then from the info panel select "search company properties".
Search the location of the council you are looking for in the search bar and navigate to location analysis on the right hand side. Under boundaries you will find ownership type to toggle on.
As shown on the key on the left hand side, any title that are showing as blue are council owned. Simply select any of these sites to load the info panel. On the info panel the council will show next to the Owner section.
In order to load the council's portfolio on the map, click on the 'search company properties'. This will plot both freehold and leaseholds titles on the map. In order to export this data simply click on the arrow pointing downwards in the top left corner. 