A British source in Japan had relationships with several intelligence services, making his ultimate loyalty impossible to establish. British analysts still accepted his reporting because it was among the best information available, but they treated it with considerable caution. A British estimate that came slightly closer to Yamato's real armament therefore does not prove that Britain had a clean or superior spy network. Intelligence quality depends on source evaluation as well as access.
Notable Point · 1:36:15-1:38:02
A compromised source and cautious naval intelligence
A multiply compromised source in Japan illustrates why access to secret information does not automatically make intelligence reliable.