Cemetery records have his death at age 84, which puts birth between Nov 1856 and Nov 1857. The headstone has 1856. The 1900 US Census has his birth as Dec 1856. The 1910 US Census has immigration to US in 1871 and being married to Cordelia for 32 years (so marriage about 1878).

Great Falls Tribune, Nov 6, 1941, Page 3, has a death notice with an error that shows birth date as 1876 and immigration to the US 14 years later (making it 1890), then states he moved to Montana in 1888. Obviously there is an error, indicating he came to Montana 2 years before he came to the US. From the other evidence it is probably just a typographic error in the birth year, it should be 1856. It also states birth place of Liverpool which is in conflict with the headstone's Bristol, Glostenshire (misspelling of Gloucestershire).

The Missoulian, Nov 4, 1941, Page 3, Column 2, has an obituary which states: He arrived in Montana in 1886 from Maryland. Was born Bristol, England, Dec 22 1856, and immigrated to the US when he was 10. Was survived by his (2nd) wife Sarah, 3 daughters: Mrs Gertrude Goodreaugh (Goodreau) and Mrs Fred Travis of Helena, Mrs Margaret Lewis of Missoula, 5 sons: Phil Prewett of Missoula, Alfred Prewett of Simmons, Thomas Prewett Jr. of Cascade, Frank Prewett and Wallace Prewett.

"Mountains and Meadows, A Pioneer History of Montana 1805 to 1925", compiled by the Cascade Historical Committee, published c.1970: The Thomas Prewett Family written by Alzory Woods Prewett (wife of son Alfred), pages 241 and 242.

Thomas was married three times. After his wife Cordelia died in 1927, he married Mary Ann Brackett. She died in 1935. He then married Sarah Lunsford in Missoula, Montana.

Thomas, his brother-in-law John Perry and their wives and children came to Helena, Montana in May of 1886. They spent their first winter in Helena. The Prewett family moved to Remini where Thomas worked in the mines. In 1892 they moved to a farm at Hardy.