Why won't Vallance and Whitty answer any questions?

In a Downing Street statement this morning, Chris Whitty and Patrick Vallance presented their take on the latest coronavirus data. Speaking without a government representative, the pair said that Brits needed to 'break unnecessary links between households' and warned that the UK could see 50,000 new coronavirus infections a day by mid-October. But why didn't Vallance and Whitty answer questions from journalists? Cindy Yu speaks to James Forsyth and Katy Balls.