After discussing with Milner, Foyle realises that the letter is coded and the address must be a letter drop for an intelligence service. Dillon denies that the addressee lives at the hotel, but offers to take the letter in case the person comes to collect it, which confirms to Foyle that the hotel is a letter drop. He says to Dillon "why would you do that?" Foyle only offers his surname because he is already known to the intelligence services, confirmed earlier in this episode, and in previous episodes. Dillon makes an immediate phone call and not long after, Foyle is picked up by Military Intelligence, Section 9 (MI9). MI9 specialised in helping British prisoners of war escape - an underlying theme of the episode.