Sherlock parody?

Hey guys,

I was on Twitter recently and I saw this tweet, which I have copied here:

David Walliams (@davidwalliams) tweeted at 9:56 PM on Wed, Nov 23, 2016:

#Sherlock as you have never seen him before. This Friday 9:30pm @BBCOne 'Walliams & Friend' starring @jackwhitehall

(I would have taken a screenshot but I cannot on my device, sorry.)

The tweet also included the following image:

Does anybody have any details about this? Or do I have to watch it to find out what it's about?