Cryptogram from Pride and Prejudice, chapter 29

"I am not one-and-twenty."

The sentence you are solving goes here.

When Lady Catherine and her daughter had played as long as they chose, the tables were broken up, the carriage was offered to Mrs. Collins, gratefully accepted, and immediately ordered. The party then gathered round the fire to hear Lady Catherine determine what weather they were to have on the morrow. From these instructions they were summoned by the arrival of the coach; and with many speeches of thankfulness on Mr. Collins's side, and as many bows on Sir William's, they departed. As soon as they had driven from the door, Elizabeth was called on by her cousin to give her opinion of all that she had seen at Rosings, which, for Charlotte's sake, she made more favourable than it really was. But her commendation, though costing her some trouble, could by no means satisfy Mr. Collins, and he was very soon obliged to take her Ladyship's praise into his own hands.