Why do you think the house had looked so gloomy on the first evening and so different the next morning? Chapter 7

From the text:

And yet he lied as he said it, for it chanced that after breakfast I met Mrs. Barrymore in the long corridor with the sun full upon her face. She was a large, impassive, heavy-featured woman with a stern set expression of mouth. But her telltale eyes were red and glanced at me from between swollen lids. It was she, then, who wept in the night, and if she did so her husband must know it. Yet he had taken the obvious risk of discovery in declaring that it was not so. Why had he done this? And why did she weep so bitterly? Already round this pale-faced, handsome, black-bearded man there was gathering an atmosphere of mystery and of gloom. It was he who had been the first to discover the body of Sir Charles, and we had only his word for all the circumstances which led up to the old man's death. Was it possible that it was Barrymore, after all, whom we had seen in the cab in Regent Street? The beard might well have been the same. The cabman had described a somewhat shorter man, but such an impression might easily have been erroneous. How could I settle the point forever? Obviously the first thing to do was to see the Grimpen postmaster and find whether the test telegram had really been placed in Barrymore's own hands. Be the answer what it might, I should at least have something to report to Sherlock Holmes.