The Dalek supreme was borrowed from Terry Nation, who had acquired it from a theatre prop sale, whose Daleks for their stage production had been constructed by Shawcraft, who had made the very first Daleks for the BBC, and they had also been hired out to the Dalek movie 'Daleks' Invasion Earth 2150 A.D.' to make up the numbers, too, so they'd really gotten around. Over the years, after many makeshift repairs, this particular Dalek's neck bin has no vertical supports or angled rings, it's eye is replaced by an Everyready torch, and it's dome lights are inverted jam jars with inserted purple gels, giving it a highly unusual appearance. Also, it seems to have terrible trouble managing to flash its lights (possibly a faulty switch), or easily turn its head, so it would appear it was not exactly screen ready. Still, it's strangely impressive.
Contrary to popular belief, the Dalek Supreme featured in this episode was not actually a movie Dalek, whilst it did appear in Daleks Invasion Earth 2150 A.D. it was not constructed for that Movie, originally it was a Black Dalek Supreme for a stage play Called Curse Of the Daleks, it was then repainted Gold for its appearance in the movie, afterwards the prop was returned to the Stage play company but was then along with 3 other props purchased by Dalek Creator Terry Nation, however at some-point the skirt section was damaged and replaced, the prop was subsequently painted Red but when it was loaned for the use in this stories production it was painted Gold and Black and received numerous modifications to let it stand out from the other Daleks seen. This makes this the only known Dalek prop in history to be featured in TV, Movie and Stage productions.
This episode was watched by 8.5 million viewers on its original transmission.
This episode takes place on Spiridon in the 26th Century.