|Fig. 1: Emily Eden in 1835 (age 38)|
In the process of writing his four volume biography of Pitt, the 5th Earl Stanhope attempted to gain access of Pitt's correspondence with Lord Auckland regarding his attachment to Eleanor Eden. In the 1860s, the letters were still in the possession of the Eden family, and Stanhope was unsuccessful in perusing them. When the Auckland Correspondence was published around the same time, the letters in question were not included, but merely alluded to in passing.
Based on what he could gather without having personally seen the letters, Stanhope believed that Lord Auckland would have had great advantages to gain if Pitt had married his daughter. Furthermore, he saw the matter as Auckland pressing the point with too much “urgency.” 
To justify his position, Stanhope poses these questions:
“I would ask then:
1. How unless on my supposition can we explain the extreme repugnance of the Eden family to produce these letters? Their insertion [in the printed Auckland Papers] would have greatly added to the interest & to the sale of the published volumes. On what ground can they be withheld, except because they contain some things not quite to the credit of Lord Auckland?
2. In like manner how otherwise explain that as Miss Emily Eden states in her letter to me of April 4, 1861 her sister, then Countess of Buckinghamshire - a lady whose high-minded character was acknowledged by all - “had the greatest dislike to the whole subject”?
3. It is stated in the “Post-script” to the fourth volume of the Auckland Papers that “a long & painful discussion took place” between Lord Auckland & Mr. Pitt. What else was to make it painful?
4. In the same Postscript we find that Lord Auckland “was naturally anxious the marriage should take place.”
5. The short narrative in the Auckland Papers (at vol. iii p. 374) says that “several letters passed between Lord Auckland & Mr. Pitt suggesting arrangements by which the marriage might in time take place without impudence.” It is clear that these suggestions must have come from Lord Auckland & not from Mr. Pitt, who in his first letter of which extracts are given had declared the obstacle arising from his pecuniary embarrassment to be “insurmountable.” 
Stanhope makes a valid point in thinking that Auckland had much to gain from a marriage between his eldest daughter and William Pitt (who was then Prime Minister). Lord Auckland could be a political turncoat, changing sides frequently, and intriguing to gain a greater position for himself. Nevertheless, as I have seen the painful letters in question, and can vouch for the painful nature of the draft letters, I disagree with Stanhope in that I believe Pitt's heart was involved.
|Fig. 2: The Hon. Emily Eden in later life (1860s)|
Stanhope refers to a letter from the Hon. Emily Eden (1797-1869) dated Norwood, April 4, 1861. In an extract of her letter to Stanhope, she mentions the affair between Pitt and her deceased sister, and mentions the unpublished letters:
“…As for Mr. Pitt’s attachment to my sister, I hardly know till I go home, what information I can give you. I should think not so much as Lady Hester Stanhope does. My sister had the greatest dislike to the whole subject - and was so urgent against any mention of it, that it would be impossible to publish Mr. Hogge’s determination to have them for the two next volumes of my father’s correspondence that I don't think her family would be justified in giving to the public such very private letters. I have not looked at them for some years but my recollection of Mr. Pitt’s letters is that he expressed very strong affection for my sister, but that his pecuniary distress made it quite impossible he should marry, and that every visit to Eden Farm added so much to his unhappiness that he thought it would be prudent to remit them for a time. When I go home next week I will look at them again and let you know the result.” 
There is no further correspondence on record between Emily Eden and Earl Stanhope, so it can be deduced that she never got back to him. It was many years before those "very private letters"  ended up at the British Museum (and then the British Library).
What is interesting is Emily's reference to her sister having "the greatest dislike to the whole subject - and was so urgent against any mention of it..."  Perhaps this was due to the painful nature of the breakup. Pitt ended it, and it is doubtful whether they ever saw one another again. As a consequence, Eleanor may rightly have felt anger, pain, and resentment toward Pitt. The report of their intended marriage was widely known, and she would naturally have felt pain and embarrassment as a result of the marriage not taking place. If her heart was involved she would have been highly upset. We don't have a record of Eleanor's feelings; Lord Auckland mentioned her not being able to quit her rooms for several days, so it may be argued that she had feelings for Pitt as well. Either way, it is understandable why Eleanor would want to avoid the subject as much as possible - even many years later - and especially if it was a difficult experience.
1. Attachment of Mr. Pitt to the Hon. Eleanor Eden 1796-7 "Memorandum stating the conclusion to which I have come on the whole case. Stanhope. December 1874.”
3. Mr. Pitt & the Hon. Eleanor Eden - January 1797 - Letter to Earl Stanhope from the Hon. Emily Eden, 1861; Correspondence thereupon with Miss Eden. U1590/S5/C60/20.
Figure 1: Emily Eden by Simon Jacques Rochard (1835). NPG 6455. Source
Figure 2: Emily Eden by John & Charles Watkins, after George Richmond (1860s). NPG Ax46419. Source