the relative pronoun “that” (l.1) can be correctly replaced by which.

the determiner “any” (l.1) means some.

the noun “Circle” (l.1) functions as an adjective.

the pronoun “one” (l.21) refers to docudrama.

the word “its”, in “of its kind” (l.20), is the full form of it’s.

the spelling of the words “programmes” (l.18) and “dramatised” (l.21) indicates the use of British English.

the modal disjunct “probably” (l.13) expresses the author’s view on how likely it is that what follows this word is true.

the adjective “ordinary” (l.9) is synonymous with unusual.

the expression “fly-on-the-wall” (l.7) means to be able to watch what people are doing without their noticing you.