I think Adam Hall has made something of a misstep with setting up the mission in TSS, related primarily to the climate of fear Q encounters upon coming back to the Bureau after Norton snags him from his leave.
Mind you, for years I've thought it very effective, and I think I know why he did it, and before I started delving into the novel in detail, I thought there was consistency between the pall cast across the Bureau over the Shapiro affair and what they wanted Q to do.
But there is no such consistency. At the time Q is sent out, the Bureau suspects strongly that Shapiro has not been sent back to Lubyanka, that he is likely to have faked his capture from Hannover, that he's passed himself off to dissidents as a representative of British intelligence, and furthermore that the chief danger connected with him does not have to do with him being picked up and grilled about the Leningrad cell; after all, he'd already taken the worst hits the K could give him and stayed (relatively) sane, something the Bureau's known for a while. "Our information," Bracken finally admits, "has been coming in for quite a time, and from more than one source."
So here's my problem. At least some of the Bureau would have to be in the know about this; even if not told directly, they could work it out for themselves, since Schrenk would've had to've used resources either at the Bureau (documentation, raw intelligence, access, so forth) or British facilities behind the Curtain in order to get back into the target area (look at the trouble Quiller has to go through, even with the ultra-competent Croder's "all possible" support).
So: what is it that everybody's so afraid of? What causes Tilson to look "frightened to death" [01:57], Jessop to turn white [01:76], and O'Rourke and Wallis to clam up [01:82, 84]? It's one thing for Hall to want the reader to think that the danger is from Schrenk getting in the hands of Auntie KG again (until a couple of weeks ago, that's what I always thought), but it's another to make that a point of an official policy which appears to frighten everyone. The flaw here is that the narrator (Q) sees his colleagues scared; yet the reason for their obvious fear cannot be the one Croder gives Q in Tempelhof. We could assume that the execs in the Caff might not know the real story, but surely Tilson would have known. If Tilson and Croder knew, then why couldn't they have told Quiller (or Bracken, a point I'll take up later)?