Tony Gardner tweeted this (from James Cary)- It's not coming back.
http://sitcomgeek.blogspot.co.uk/2015/07/bluestone-42-over-and-out.html
Bluestone 42 - Series 3 Page 2
Never liked this show so for me its cancellation will hopefully make way for something more appealing.
I loved it. That's such a shame. 
https://www.comedy.co.uk/news/story/000001853/bluestone_42_cary_hurst_sitcom_finished/
Sad but expected news. Hohum.
Great news - it's shit!