official Google+ page is updated with a photo. He was there with Joshua McGuire to promote Rosencrantz and Guildenstern are Dead. Other guests are Ricky Gervais, Tom Hiddleston, Ruth Wilson and music from Tinie Tempah.
The show airs tomorrow on BBC One, 10:35pm (that's 23:35 for Holland).
Graham Norton ShowThe Google+ link at this page is Dan's post shared via this site's Google+ page