The Prime Minister is put on the spot by someone from the German embassy.
David Cameron says "we should be more positive" about the success of the single market.
He says he makes no apology for standing up for UK interests in Europe; it is "simply not credible" to make cuts at home and increase the EU budget.
That "does not make you a bad European", he insists. He calls for more focus on how the European Commission spends its money.
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It reportedly threatened attacks on planes "flying from Heathrow to the US" across the July 4 US Independence Day holiday weekend.
Accompanied by the Duke of Edinburgh, the Queen will attend the opening ceremony of the fifth session in the Holyrood chamber.
Ms Leadsom has received the backing of Ian Duncan Smith, the former work and pensions secretary.