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Tom Baker as The Doctor |
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Louise Jameson as Leela |
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John Leeson as K-9 Mk. I (voice) / Nucleus (voice) |
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Michael Sheard as Lowe |
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Brian Grellis as Safran |
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Jay Neill as Silvey |
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Edmund Pegge as Meeker |
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Frederick Jaeger as Professor Marius |
| Directing | Derrick Goodwin | Director |
| Writing | Dave Martin | Writer |
| Writing | Bob Baker | Writer |
| Writing | Robert Holmes | Script Editor |
| Production | Graham Williams | Producer |
| Sound | Dudley Simpson | Original Music Composer |
| Sound | Delia Derbyshire | Theme Song Performance |
