This could be called a bottle episode as only the regular cast are seen and it's almost all on the Liberator.
Not a single word is spoken until 6 minutes and 40 seconds into the episode
Along with Moloch (1980), this was the episode with the highest chart position on original UK transmission. On a season-by-season basis, then season three had the highest chart positions, averaging at 32. The first season was someway behind, at an average of 45, with season four at 73. The lowest ranked season in terms of chart position was season two, which averaged 78th position in the audience charts.