Just in case anyone was following these messages, I have discounted Thomas Radcliffe bapt. Andreas 2 Feb.1736/37 son of Philip Radcliffe [bur.1762] and Joney Teare [bur.1778] as being the Thomas Radcliffe who married [1]Margaret Skinner, and [2] Margaret Brew - the recorded grandparents of the Rev.William Thomas Radcliffe - because his brother John lived until 1802.

There was one other possible Thomas Radcliffe who fitted the age at death given on his M.I. - the same death date as in his will and at his burial. This was Thomas bapt.6 March 1736/37 a younger son of Philip Radcliffe and Margaret Brew of Ballakelly [which would fit your "well known northside family", Jane].
It is confusing having two Margaret Brews marrying two generations of the same family.

Margaret Brew no.1 and her husband Philip Radcliffe both died 1754 [wills].

Margaret Brew no.2, the daughter of Thomas Brew of Cronk-beg, Andreas, married 1777 [1] John Radcliffe their 2nd son b.1735, and had one daughter Esther b.1778. John died 26 May 1785 [will]. He may have had previous marriage(s) but Esther was the only child mentioned. Also mentioned were his wife, his brother Thomas as guardian to Esther, and his nephew Thomas Radcliffe.

MI, Andreas Old Yard: Here lieth the body of John Ratliff. Also Margaret his wife alias Brew who departed this life January 18th, 1826, aged 78 years.

In the meantime John's younger brother Thomas b.1737 had married 1772 [1] Margaret Skinner, and had a son Thomas b.1773. Margaret died 1774 [will].

MI, Andreas Old Yard: Sacred to the memory of Catherine Radcliffe alias Stephens wife of Thomas Radcliffe who departed this life the 1st of January 1821, aged 46 years. Also Margaret Radcliffe alias Skinner, his mother, who departed this life the 5th of Feby 1774, aged 29 years.
MI, Andreas Old Yard: Erected by Thomas Radcliffe in memory of his father Thomas Radcliffe, joiner, who departed this life September 17th, 1807, aged 71 years.

It appears that Thomas Radcliffe b.1737 “uncle by the father’s side” married his brother’s widow.
Thomas Radcliffe, widower, married Margaret Radcliffe als Brew, a widow, on 1 Feb.1787, in the presence of Wm Radcliffe Parish clerk and Thomas Brew.

Under British law it was illegal until the 20th century to marry your brother's widow/ sister's widower! Was it different in the Isle of Man? Do you know, Frances?
Margaret's father or brother Thomas Brew witnessed the marriage, so can't have objected.

Thanks,
Sue