How had miss Brinklow assumed that Barnard was not his real name? (Chapter Six)

From the text:

There was another silence, broken at length by Miss Brinklow’s shrill voice: “I’m sure I don’t know who you are, Mr. Barnard, though I must say I guessed all along you were traveling incognito.” They all looked at her enquiringly and she went on: “I remember when Mr. Conway said we should all have our names in the papers, you said it didn’t affect you. I thought then that Barnard probably wasn’t your real name.”