Subtle signal about how things are in the new post-Control Circus regime
Smiley sends Guillam into the Circus to get information about personnel actions that occured after Control is removed. Roy Bland is seen scurrying up to the rooftop to consult with Alaline after presumably getting word from another Circus employee that Guillam is on the premises. Immediately after we see Bland in the elevator engaging Guillam and as they exit he casually inquires, "where are you off to?" Guillam replies, "Lunch." Bland good naturedly rejoins, "Want some company?"
Alaline has sent Bland to snoop on Guillam, to try to find out what he's up to. A sign of an insecure leader and a nervous pack of cronies. This is not a good foundation for an intelligence service. Further evidence for us that all is not well in the Circus.