He is speaking to Lady Clonbrony--to Miss Nugent.

Now Lady Clonbrony is introducing him to Miss Broadhurst.' 'I see him now,' said Lady Langdale, examining him through her glass; 'a very gentlemanlike-looking young man, indeed.' 'Not an Irishman, I am sure, by his manner,' said her grace.
'Heathcock!' said Lady Langdale, 'who is Miss Broadhurst talking to ?' 'Eh! now really--'pon honour--don't know,' replied Heathcock.
'And yet he certainly looks like somebody one certainly should know,' pursued Lady Langdale, 'though I don't recollect seeing him anywhere before.' 'Really now!' was all the satisfaction she could gain from the insensible, immovable colonel.

However, her ladyship, after sending a whisper along the line, gained the desired information, that the young gentleman was Lord Colambre, son, only son, of Lord and Lady Clonbrony--that he was just come from Cambridge--that he was not yet of age--that he would be of age within a year--that he would then, after the death of somebody, come into possession of a fine estate, by the mother's side 'and therefore, Cat'rine, my dear,' said she, turning round to the daughter, who had first pointed him out, 'you understand, we should never talk about other people's affairs.' 'No, mamma, never.

I hope to goodness, mamma, Lord Colambre did not hear what you and Mrs.Dareville were saying!' 'How could he, child?
He was quite at the other end of the world.' 'I beg your pardon, ma'am, he was at my elbow, close behind us; but I never thought about him till I heard somebody say, "My lord--"' 'Good heavens! I hope he didn't hear.' 'But, for my part, I said nothing,' cried Lady Langdale.
'And for my part, I said nothing but what everybody knows!' cried Mrs.
Dareville.
'And for my part, I am guilty only of hearing,' said the duchess.

'Do, pray, Colonel Heathcock, have the goodness to see what my people are about, and what chance we have of getting away to-night.' 'The Duchess of Torcaster's carriage stops the way!'-- a joyful sound to Colonel Heathcock and to her grace, and not less agreeable, at this instant, to Lady Langdale, who, the moment she was disembarrassed of the duchess, pressed through the crowd to Lady Clonbrony, and, addressing her with smiles and complacency, was 'charmed to have a little moment to speak to her--could NOT sooner get through the crowd--would certainly do herself the honour to be at her ladyship's gala on Wednesday.' While Lady Langdale spoke, she never seemed to see or think of anybody but Lady Clonbrony, though, all the time, she was intent upon every motion of Lord Colambre, and, whilst she was obliged to listen with a face of sympathy to a long complaint of Lady Clonbrony's, about Mr.Soho's want of taste in ottomans, she was vexed to perceive that his lordship showed no desire to be introduced to her, or to her daughters; but, on the contrary, was standing talking to Miss Nugent.