1901 census with Sarah Smith and Joseph E at Denton:
https://familysearch.org/ark:/61903/1:1:X926-JCB1911 census with William, Sarah and Joseph as Ernest (occupation - iron founder):
https://familysearch.org/ark:/61903/1:1:XW1P-TK8Jamjar
AddedMarriage: 
Marriages Sep 1870 Ashton 8d 805
SMITH William to BOARDMAN Sarah
Births:
SMITH, LYDIA  ANN mmn BOARDMAN
GRO Reference: 1872  M Quarter in ASHTON UNDER LYNE  Volume 08D  Page 466
SMITH, JAMES  WILLIAM EDWARD mmn BOARDMAN 
GRO Reference: 1876  S Quarter in ASHTON UNDER LYNE  Volume 08D  Page 514
SMITH, THOMAS  HENRY mmn BOARDMAN
GRO Reference: 1878  D Quarter in ASHTON UNDER LYNE  Volume 08D  Page 518
SMITH, ANNIE  MARIA mmn BOARDMAN 
GRO Reference: 1881  J Quarter in ASHTON-UNDER-LYNE  Volume 08D  Page 499
SMITH, FRANK mmn BOARDMAN     
GRO Reference: 1885  M Quarter in ASHTON UNDER LYNE  Volume 08D  Page 541
SMITH, JOSEPH  ERNEST mmn BOARDMAN 
GRO Reference: 1891  S Quarter in ASHTON UNDER LYNE  Volume 08D  Page 497
Added: All six children still living in 1911, as per census image.