I suspect that you are thinking of Thomas Hewitt who lived on Sheriff St. in Saint John, New Brunswick. He appears on that street in the directory of 1865 as a blacksmith, and in 1867 as a filer (sharpener of saws.) In 1871 he is Thomas Hewett, still a filer, on Sheriff St., Portland (now part of Saint John), Saint John Co., NB. According to several newspaper extracts by Dan Johnson:
Thomas and Margaret Hewitt of Sheriff St. had a daughter, Eliza, who d. Portland, saint John Co., NB MAR1869 age 17 years.
Thomas Hewitt of Sheriff St. d. 1JUL1875 age 60 years.
A son was William Hewitt who d. 3NOV1872 age 18 years.
Their eldest daughter, Mary Ann Hewitt, d. 22NOV1870 age 19 years.
Thomas' wife, Margaret Hewitt, b. Lismore, County Wexford, Ireland ca. 1801, d. Sheriff St., Portland, Saint John Co., NB 5DEc1874 age 73 years.
All were residents of Sheriff Street.
I can find no clear indication of a Thomas Hewitt/Hewett in the 1891 census of NB. Nor in the 1901 or 1911 returns. There is no Thomas Hewitt or Hewett listed in the on-line version of NV Vital Statistics.
I would suspect that, if Thomas were, in fact, a sheriff in New Brunswick he would receive more notice. The above Thomas Hewitt is apparently not the one you seek, but seems to be the one you have been pointed towards. If you find anything new, let me know.