Rachel Brownstein, writing in The Cambridge Companion to Jane Austen notes that
[Henry Tilney] is dominated and intimidated by his overbearing father, the General, himself 'a very handsome man of commanding aspect, past the bloom but not past the vigor of life.' It is General Tilney, not his son, who pointedly relishes Catherine's physical attractions, appreciating the elasticity of her walk - and causing her to walk on 'with great elasticity, though she had never thought of it before.'
Indeed, it seems that while Henry Tilney is on about the price of muslin, his father is the one who notices Catherine and first considers her as a wife for his second son (of course, for mistaken reasons). His worldliness provides a counterpoint to the naivete of Catherine and Henry and the convergence of his motive and Catherine's are, as Brownstein also notes, "among the nice ironies that make this romance so cheerful."
