This wasn't really the tall, lean man's fault; he knew very little about Russell Benjamin. When he set out on the mission, all he had was a business card and wasn't even clear about what Russell Benjamin looked like. He could only monitor the apartment day and night, waiting for the other party to return.
London is so vast, with millions of people. Searching for a man he had never seen in this vast sea of people was just like looking for a needle in a haystack; the tall, lean man was out of options.
Up to now, he didn't realize that he had been exposed. While he was monitoring the apartment, a group of Kitty was also surveilling him from above.
"Forget it, regardless, you have at least brought back an important piece of information."