http://www.survivorstvseries.com/What_Is_Survivors.htm

Website also has episode synopses..

What is Survivors?
The original or 'classic' Survivors was an 38 episode drama series which aired on BBC1 between 1975 and 1977.
The opening episodes were first broadcast on BBC1 in April 1975 and immediately grabbed the attention and interest of the viewing public.
In essence, the series concerns the aftermath of a plague which had wiped out over 99% of the world's population and the experiences of a group of individuals in England as they grappled with the post-plague world and the trials of day-to-day survival.

From Wipekedia ... It concerns the plight of a group of people who have survived an apocalyptic plague pandemic, which was accidentally released by a Chinese scientist and quickly spread across the world via air travel.
Referred to as "The Death", the plague kills approximately 4,999 out of every 5,000 human beings on the planet within a matter of weeks of being released.
Since its original broadcast the series has gained a cult following.