The reaction of the members of the grid at the end of Spooks 9.8 seems very ambiguous to me. Harry still is shown to be on the roof and the knowledge the other grid members have, is not absolutely clear.
I not for a moment had the impression they were mourning Lucas / John.
Ruth is crying because Harry is safe again. The others are content, that everything is over and they are still alive. For them Lucas really was nothing. To Ross at least he had a friendly connection as colleague and a common understanding of work ethics. With the others he shared nothing at all.
Harry Pearce did not trust Lucas and he in return did not trust him.
Dimitri Levendis was not in the group long enough for Lucas to establish a connection with him.
Beth could have been interesting, but it did not work out that way.
Ruth he clearly mistrusted as she did him. But why? Was it only because he feared detection by her?
They also had a completely different approach to work. Ruth with all her brilliance has a very intuitive and unorthodox way of research whereas Lucas very much associated with the systematic approach with which Ross had been leading section D.