I just did another rewatch of my Callan disks, and I thought a post of some screen captures of the show might be of interest.
Being located in North America, regional dvd's were limited to two seasons:
The first set has several instances of Callan, portrayed by actor and wargamer Edward Woodward, showing his model soldiers.
In one episode of the first set, "Act of Kindness", Callan attends a wargame convention.
Here's some of the screen shots:
Callan had to " convince" a businessman to step aside and allow a sleazy co worker advance because he was considered an asset by the government.
Callan mentions the magazine "Miniature Warfare".
The figures are a mix of Airfix conversions and 20mm metal.