This is one of the greats.
Files replaced with an upscaled version
When I first saw this in full, I thought the first series was the best. Funnily enough, the next time I watched it full, I found myself preferring the second series! Though both series have two big respective bonuses - John Gordon Sinclair and Richard Wilson.
I enjoyed this series overall so much I double-dipped for the physical releases of this - the original separate series releases, and then the repackaged release with the two series discs housed in the same case.