In the books, Strike’s office is situated above the 12 Bar Club, which is now boarded up after closing down in 2015. For the TV series they used number 6 Denmark Street instead,with its guitar shop (No Tom Guitars) directly below.
Filming took place here for every episode. In the Silkworm, this is where Strike gives Robin her Christmas present and gives her a kiss on the back of her hand.
In Career of Evil, there was the scene at the beginning of episode 1 where the killer delivers a package containing a severed leg to Robin on the doorstep of their office.
You can find Denmark Street on Google Maps here.