In this task, you're given a context, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both context and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the context or linked information.
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Question: Context: He was the son of Henry Andrade Harben and the grandson of Sir Henry Harben Link Information: Henry Andrade Harben FSA (12 August 1849 - 18 August 1910) Answer: 26

Answer: What is the age difference between Harben's father and grandfather?


Question: Context: . Real executive power vests in a Union Council of Ministers Link Information: none Answer: none

Answer: How many members comprise the council in which real executive power is vested?


Question: Context: spin-off show Holby City Link Information: Casualty, stylised as CASUALY, is a British medical drama series that airs weekly on BBC One. It is the longest-running emergency medical drama television series in the world, and the most enduring medical drama shown on prime time television in the world. Created by Jeremy Brock and Paul Unwin, it was first broadcast in the United Kingdom on BBC One on 6 September 1986.  Answer: 13

Answer:
How long had Casualty been airing before its spinoff first aired?