They're quite like 'Invasion', which was the pilot for the new direction that Derrick Sherwin and Peter Bryant wanted to take the show, influenced by the popularity of sf/fantasy shows aimed at adults, such as Avengers and The Man from UNCLE. When Barry Letts was fully in charge for the second Pertwee series, he decided to reposition the programme back to being more of a family show.
Though I think the length of those stories is as much to do with budgetary issues (fewer longer stories being cheaper) than a deliberate stylistic move. And whilst seven episodes is longer than I think is the ideal (four to six), stories of that length weren't unprecedented in 1970 ('Invasion' had eight, and 'War Games' ten, though in both cases that was due to the short notice falling through of other stories. And I personally think 'Inferno' drags less than 'Ambassadors of Death' and 'Silurians'.
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Though I think the length of those stories is as much to do with budgetary issues (fewer longer stories being cheaper) than a deliberate stylistic move. And whilst seven episodes is longer than I think is the ideal (four to six), stories of that length weren't unprecedented in 1970 ('Invasion' had eight, and 'War Games' ten, though in both cases that was due to the short notice falling through of other stories. And I personally think 'Inferno' drags less than 'Ambassadors of Death' and 'Silurians'.