Hello Shelagh, and welcome to the site, hope this info will help, not always easy searching for ancestors!
Similar to Lynne, took a look at ancestry but discovered another James McGuirk!
James McGuirk living in Molyneux Street Bootle 1891;
James McGuirk - head aged 47
Mary McGuirk - Wife aged 47
Elizabeth McGuirk - daughter age 15
Annie McGuirk - daughter age 8
James McGuirk - son age 10
Michael McGuirk - son age 5
The following census 1901 gives no mention of James McGuirk senior, but the 1911 census shows Mary to be widowed!
Family by this time are living in Lyon Street, (surely can't be a coincidence) living in same street as your grandfather Peter Foy!!
Mary McGuirk - head of house age 55
Elizabeth McGuirk - daughter age 25
James McGuirk - son age 20
Annie McGuirk - daughter age 18
Michael McGuirk - son age 15
Mary A Gallagher - lodger age 47
The 1871 census shows the family to be living in Dun or Dunn Street, Bootle,
1911 census, remainder of family were still in Lyon Street, but this time, Street renamed, Beresford!!
Will p.m. rest of information, as it can be quite lengthy