Mrs. Gardiner had seen Pemberley, and known the late Mr. Darcy by character perfectly well. Here consequently was an inexhaustible subject of discourse. In comparing her recollection of Pemberley with the minute description which Wickham could give, and in bestowing her tribute of praise on the character of its late possessor, she was delighting both him and herself. On being made acquainted with the present Mr. Darcy's treatment of him, she tried to remember something of that gentleman's reputed disposition when quite a lad which might agree with it, and was confident at last that she recollected having heard Mr. Fitzwilliam Darcy formerly spoken of as a very proud, ill-natured boy.
Mrs. Gardiner provides a confirmation to Wickham's story. Her opinion is of value because she
was an amiable, intelligent, elegant woman, and a great favourite with all her Longbourn nieces. Between the two eldest and herself especially there subsisted a very particular regard.
However, I think it very interesting that "she tried to remember something of that gentleman's reputed disposition when quite a lad which might agree with [Darcy's mistreat of Wickham]. To me, it means she really to think about, to come up with anything bad about Darcy and only has possible hearsay to back it up. But I wonder how confident her memory really is.