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As far as the visa for the Schengen area is concerned, the UK is primarily interested in whether you will be able to complete your travels as intended. They will be far less concerned about whether your previous stay in the Schengen area was authorized than about whether you will be able to return there as planned.
In both cases, however, they are no more concerned about whether the visa is in a valid passport than are the authorities of Schengen countries. That is to say, if the visa is valid in the jurisdiction that issued it, the UK will consider it to be valid.
As long as you have both passports with you, and show them as needed, you should not expect any trouble related to the fact that your Schengen visa is in an expired passport or that it is in a different passport from your UK visa.