Although there was a 72 yr William Rowan that died in 1915, I think your William died the following year, based on the cemetery records:
Kirkdale Cemetery, Liverpool
William Rowan, buried March 11,
1916, age 73, 57 Emery St.,Walton Section 7 plot 546
Barbara Theodosia Rowan buried January 31,
1943 1934, age 83, 9 Birdhall (or Birdhill) Rd, (Cedar Hill?)
Section 7 plot 546
ROWAN, WILLIAM 73
GRO Reference: 1916 M Quarter in WEST DERBY Volume 08B Page 495
If you have based his birth year on census ages, they are commonly a bit off. The 1911 census puts his age at 68, so either 1842 or 1843 depending on what month he was born
1911 census:
https://www.familysearch.org/ark:/61903/1:1:XWT6-N6VLadyhawk noted a possible first marriage to an Eliza Hills. If that was him, it is possible that they had at least one child. The mother is Elizabeth as opposed to Eliza, but worth ruling it out.
https://www.familysearch.org/ark:/61903/1:1:F52X-DZH (Susanna)
Tread carefully; there seems to be a LOT of William Rowans running around that fit his age and location!
Edited to correct DoD for Theodosia.
