I first saw Department S perhaps twenty years ago while doing work experience at a studio in London dealing with dvd restorations.. instead of watching what the audio guy was doing I spent more time enjoying this great show
I liked it even more once i realized Peter Wyngarde (Klytus from Flash Gordon) was Jason King and so purchased a really great restoration of Department S by network just recently, and what a treat it is.. it has cleaned up really well and is just a perfect snapshot of the late 60's
I'm a big fan of shows like The Avengers too but I actually prefer the lesser known Department S a little more now since the storylines are a tad more serious and more James Bond / Ipcress File styled
The 3 main characters are all great, the head of Department S who appears sometimes is also excellent
The production values of the show are high class.. good sound and dialogue, lovely late 60's interior designs. Attention to detail was even paid to things like making the views outside moving cars look reasonable and consistent given what else was going on at the time
Department S also has good humour and is of course lusciously retro