Catching up with this news. I think it means Whitty and Valance will be trotted out to explain data, graphs and trends and impress on the public that things are about to get a lot worse (especially if people don't comply with restrictions). Perhaps the Cabinet have decided to try the scientists first hoping that the public will take them more seriously, after all it's becoming obvious there's unrest and many people aren't complying as they are (depending on your opinion) rightly or wrongly fed up with the way things are.
They have a higher profile than Boris and so he's been left out for this briefing - but then I fully expect him to make an appearance very soon, in order to announce more restrictions - maybe he'll have Sunak with him with some economic measures to sweeten any further lockdown.
It's quite possible that if enough people get it in their heads not to comply, there's no way they can be stopped, and we can see the numbers of people willing to ignore any advice is growing daily. Unfortunately this govt isn't being taken seriously and have made serious errors, the worst being the messed up testing system, if you can even call it a system.
I don't think whatever Whitty and Valance say today will be enough to stem the rising tide of discontent.