Anniversary question

It was exactly a year ago that I visited this building for the first time. There is nothing in the picture which explicitly states what this building is. But the colour scheme, plus that Black Maria (okay, it is painted blue, but it was a paddy wagon alright) parked on the right should give you enough indication for making a guess. 

Here are some more clues. The original building, the core of which has been retained here, was built in 1842. In 1856, it was repurposed and continued to function as a key office until about 2012-13, after which it was unused for a while. In 2018, a restoration programme was begun, which brought the building to its current shape - and purpose - in 2021. 

So go ahead, make that guess and tell me what this building currently is. And for bonus points, what office was operating from here between 1856 and the early 21st century!

I guess you would have figured out more clues in the labels!