Letters from HLP to members of the Williams family of Bodelwyddan (neighbours to the Piozzis at Brynbella), namely Lady Margaret Williams, Miss Margaret Williams and Sir John Williams. In the letters, HLP gives a chronicle of her daily life and family concerns, and comments on public events (particularly the war with Napoleon and the threats of invasion and of revolution). Her visits to London and to Bath provided news of friends and descriptions of the entertainments and fashions of the day. The Williams family themselves proposed a posthumous edition of the letters they had received, but their plan was abandoned following a threat of legal action by HLP's adopted heir, Sir John Salusbury Piozzi Salusbury.
The letters were bound into eleven volumes by the Chester bookseller J. Seacome, shortly after HLP's death in 1821, probably in preparation for the intended publication. The letters are mainly guarded into the volumes attached to short stubs; however, all the volumes contain miscellaneous letters and verses (most undated) pasted onto the boards and flyleaves, probably at a later date. Each volume contains the bookplate of John Williams, Bodelwyddan, on which has been marked in pencil a letter identifying the volumes in a sequence A to K.
Letters dated 1796-1818 from HLP to Lady Margaret Williams (1768-1835), wife of Sir John Williams (1761-1830), First Baronet. Comprising five volumes as follows:
- Volume A, numbered 1-42, 24 November 1796-30 January 1802 (guarded) and undated (pasted);
- Volume B, numbered 1-51, 18 March 1802-28 November 1806 (guarded) and 1801 and undated (pasted);
- Volume C, numbered 1-52, 10 February 1807-25 November 1811 (guarded) and 1810-1811 and undated (pasted);
- Volume D, numbered 1-43, 4 January 1812-20 January 1818 (guarded) and 1813 and undated (pasted);
- Volume E, numbered 1-59, all undated.
Letters dated 1796-1818 from HLP to Miss Margaret Williams (1768-1835) of Bath, sister of Sir John Williams. Comprising five volumes as follows:
- Volume F, numbered 1-56, 18 May 1806-19 May 1808 (guarded) and February 1807 and many undated (pasted);
- Volume G, numbered 1-60, 15 July 1808-24 November 1812 (guarded) and 1814, 1816-1817 and many undated (pasted);
- Volume H, numbered 1-60, 1 January 1813-24 November 1815 (guarded) and 1815-1820 and many undated (pasted);
- Volume I, numbered 1-72, 14 January 1816-[25 December] 1819 (guarded) and 1816-1818 and many undated (pasted);
- Volume J, numbered 1-60, 17 January 1820-9 April  (guarded) and 1816-1820 and many undated (pasted).
Letters dated 1813-1821 from HLP to John Williams [later Sir John Hay Williams (1794-1859), Second Baronet], eldest son of Sir John Williams. Comprising one volume as follows:
- Volume K, numbered 1-32, 3 August 1813-5 March 1821 and undated (guarded) and two undated items (pasted).