Potter refers to Drake (who makes it clear he doesn't need anyone, least of all, Potter's assistance), as "(London's) 'Lone Wolf'. This is a slight nod, as Lone Wolf was one of the names originally planned for the series, and in some markets (Italy, for one), the series is known as 'Lone Wolf'.
In quick succession, Drake mentions the (the first of 2) titles; I, too, can 'Say It With Flowers', followed by the next sentence -spoken by Edwards; 'is he following? Like a Fiish On The Hook' (episode titles are capitalised).
The 'poetry of death' Kabuki scene is really Act 5, Scene 2 of Hamlet.
Both the colour episodes of Danger Man that were produced only credit Ralph Smart as creator of the series. Nowhere on the credits does it actually state that he was involved in their production.