All the episodes made up to this point were known as series one.

Despite the program's long run, less than 24 episodes are known to exist.

Only eight episodes from the three series are known to still be in existence.

All the other episodes are known to exist in private hands.

Only 23 episodes of the radio show are known to survive.

No episodes of the series are known to have survived.

The show is believed lost, no episodes are known to exist as of 2009.

The first episode which took place was known as a thirty minute war.

Some episodes are known to be modeled on true events.

Only 75 episodes are known to exist in recorded form.