Lord Geidt's resignation comes as the government faces pressure over its asylum policy.
Home Secretary Priti Patel has said preparations for the next flight to take people to Rwanda have begun - despite last night's European court ruling that prevented a plane, already on the runway, from taking off.
Critics of the policy say the court's decision is a significant setback for the government's plans to remove asylum seekers.
The Home Secretary called it “disappointing and surprising”.
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