"Then I'll simply tell them myself when I return to England. After all, I plan on telling Mister Norrell about this."

But that's different and Strange knows it. It's best to not hide one's experiences with the fae when you and your friend are possibly going to be dealing with the fae for the next who knows how long. Back in England...he's certainly somebody will end up summoning a faerie. There's too much magic there and too many people who follow his ideas for it to not happen. But at least for Childermass, it's less of an inherent danger than it is for Strange.

"Still though, you should tell them eventually. If only because some of my exploits would serve as what not to do!"