Our listings are based on the way the episodes were broadcasted, not the way they were produced.

How were this episode advertised at the time of its original broadcast in 1979 ? On the current BBC page, this episode is listed as a special episode.

Originally broadcast in order I've listed, as shown here, displaying original release dates. I've updated episode overview in question for clarity, as well as episode 4, which was delayed until following week, which I noticed needed correcting on TMDB.

Note also that listing S01E08 needs deleting as it is a Christmas Special (don't be fooled by date being following week), which I've added to Specials and adjusted season finale status in Season 1. Status of episode listed here.

As indicated, we need to know how these episodes were advertised by the BBC at the time of their original broadcast.

Wikipedia is not an official source.

BBC listings (sourced from Radio Times) for aforementioned Christmas Special and delayed Spanish Fly.

Most significantly, notice how beginning of Season 3 is described just over a month later.

@GreatReset said:

BBC listings (sourced from Radio Times) for aforementioned Christmas Special and delayed Spanish Fly.

There are no mention that the delayed Spanish Fly is part of the second season.

Consequently, it should be listed as a special episode like it is listed on the current BBC page.

I will move it there later this week, unless you have time to do it before.

Further insight on Spanish Fly regarding both frequent erroneous listing and its broadcasting during repeats in its originally intended placing.

It should also be noted that Series 3 has a different opening sequence to the previous two, as well as a new actor playing the character of Dad, which also clearly show the episode to belong to Series 2.

@GreatReset said:

Further insight on Spanish Fly regarding both frequent erroneous listing and its broadcasting during repeats in its originally intended placing.

As indicated above, taking in account that there are no mention of a season at the time of the original broadcast and that the current BBC website list it as a special episode, it should be listed here as a special episode.

It should also be noted that Series 3 has a different opening sequence to the previous two, as well as a new actor playing the character of Dad, which also clearly show the episode to belong to Series 2.

This has no influence. The season numbering is determined by the original broadcast, not by the way the episodes are produced.

@superboy97 said:

I will move it there later this week, unless you have time to do it before.

The necessary changes have been done.