Barlow at Large began as a three-part self-contained spin-off from Softly, Softly: Taskforce in 1971 with Barlow co-opted by the Home Office to investigate police corruption in Wales.
He also had to deal with the political machinations of the senior civil servant Fenton (Neil Stacy).
In 2015 BBC's Genome Blog noted that as well as a new title the final two series also saw an effort to make the series "more action-packed and modern" including by giving it a "new title sequence and theme tune".
The BBC's Genome Blog argued that the series suffered from the fact that "the concentration on Barlow alone" did not have the same appeal as the earlier series featuring Barlow noting that "the long-running sparring with Watt was hard to replicate".
[1] The Barlow character was seen again in the series Second Verdict in which he, along with his former colleague John Watt (Frank Windsor), looked into unsolved cases and unsafe convictions from history.