Trevethow, sometimes called the manor of Lelant and Trevethow, anciently belonged to the family of Bottreaux. In 1295, Edward I. granted a market to the then lord of the manor, William de Bottreaux, to be held at La Nant, now Lelant town, on Thursdays. Trevethow afterwards became the property of the Godolphins, from whom it passed to the Praeds.

William Praed, of Trevethow, gentleman, died in 1620, leaving by Prudence his wife one son, James, and three daughters. James Praed, the son, took an active part in the civil wars on behalf of Charles I. At the restoration his name was included in the list of Cornish gentlemen proposed to he honoured with the order of the Royal Oak; his estate being valued at that time at £600 per year. He was sheriff for the county under the Commonwealth, in 1654, and elected M.P. for S. lves in 1660 and 1661. John Praed, probably a younger son of the member for S. Ives, also represented that town in several parliaments. He died in 1717, when Trevethow and other property of the Praed family went to the Mackworths of Glamorgan. There are two distinct accounts of the passing of the Trevethow estates to the Mackworths; first,— “The last male heir John Praed, Esq., M.P. for S. Ives in 1708 and 1710, died in 1717, leaving a daughter and heir, Martha, who married William Mackworth, Esq., third son of Sir Humphry Mackworth, Knt., and had three Sons.” Second,— “The family became at last represented by two brothers; the elder distinguished as Colonel Praed, married a Basset of Tehidy, but died soon after, leaving all the personal property to his widow. The younger brother succeeded to the real estate; but having been unsuccessfully engaged in trade, and finding the farms mostly leased on lives with the payment of small quit rents, according to the custom of those times, he became more and more embarrassed; till meeting with a gentleman of the family of Mackworth, in Glamorganshire, bred to the higher department of the law, he arranged with this gentleman, that on being freed from all pecuniary difficulties, and receiving a certain annuity for life, the whole Cornish estate should be transferred to Mr. Mackworth; on the further conditions of his taking the name of Praed, and what seems almost ludicrous, of his engaging, so far as the consent of one party could be sufficient, to marry Miss Penrose, of Penrose, near Helston, the heiress-at-law to Mr. Praed’s estate.”

The latter is considered the more reliable account. At Mr. Praed’s death Mr. Mackworth came into possession, and having performed every engagement to the utmost of his power, he went to Penrose with an intention of consummating, so far as lay in his power, the final condition of his inheritance; he however not only did not succeed, but found some difficulty in escaping with his life.

The validity of the transfer of the property was ultimately disputed on the part of Miss Penrose; but at the trial an arrangement was made between the claimants. Miss Penrose married William Pearce, Esq., of Penryn, and their sole heiress, Grace, married Alexander Cumming, Esq., of Altyr, in Elgin, ancestor of Sir William Gordon-Cumming, Bart.

Mr. William Mackworth-Praed settled at Trevethow, where he was succeeded by his son, Humphrey Mackworth-Praed, Esq., one of the most distinguished men of his adopted county. He was M.P. for S. Ives, 2 George Ill., 1761, and for the county 13 George III, 1772. He married Mary, daughter of William Forrester, Esq., and relict of Sir Brian Broughton-Delves, Bart., of Broughton Hall, Stafford, and had six children.

William his eldest son and heir; Herbert, rector of Ludgvan, who died early in life and four daughters,—Catherine, Mary, Arabella, and Julia.

Mary married the Rev. Wm. Sandys, vicar of S. Minver, and died without issue. Thee other three never married.

William Praed, Esq., the eldest son, married Miss Backwell, of Tyringham, in Buckinghamshire, who eventually became sole heiress to her very wealthy family. He represented S. Ives in six parliaments, and Banbury in one. To Mr. Praed the nation was indebted for the construction of the Grand Junction Canal, a medium of transit of great importance before the days of the railway.

Mr. Praed died in 1833, and was succeeded by his son, James Praed Esq., M.P., for Buckinghamshire, the county in which ho chiefly resided. He married Miss Chaplin of Lincolnshire, by whom he had several children.

William Backwell-Tyringham, Esq., son of Mr. James Praed, has dropped the Cornish adjunct of Praed; and although the proprietor of the mansion and grounds of Trevethow, and other valuable property in its immediate neighbourhood, he has made Tyringham his home.

It is somewhat singular, that after a residence of more than a century in this county, no permanent connexion has been formed by this family, nor one relative left behind.

Trevethow House is one of the most pleasantly situated mansions in West Cornwall it is surrounded with plantations, and overlooks the estuary of the Hayle. The house was almost rebuilt by Humphrey Mackworth-Praed Esq., in 1761, who displayed considerable taste in its decorations; the front, which is ornamented with a pediment, is built of native granite ashlar. To this gentleman Cornwall is indebted for the introduction of the pinaster fir, the Pinus Pinaster or maritima of Linnæus.

The arms of Pinned of Trevethow, are— Azure, six mullets argent 3, 2, and 1

The arms of Mackworth,— Per pale indented sable and ermine, on a chevron gules five crosses patée or.

The arms of Tyringham,— Azure, a saltire engrailed argent.

The arms of Backwell,— Argent, on a chevron sable three covered cups or.

The above coats of arms may be found on the funeral hatchment of William Praed, Esq., in the church.

Extract from

https://west-penwith.org.uk/lelant2.htm