The good news [of the birth of Robert O. A. Milnes] 'amazed' them, and 'made Mary Thornhill & others redden with joy': Annabel had given the impression that the birth would be later. The other Milnes children and their cousin Georgy's reactions.
Postscript: Jane still at the Melvilles at Roehampton, perhaps she will get to see the baby. Sure Annabel will 'rise in the Admiral's [perhaps Samuel Thornton?] estimation (he is here) not from giving birth to an heir, but for her extreme punctuality - which with him is the highest of virtues.