Hello Sifer,
Do you know when your father emigrated to Canada? There is a possible immigration record for the family in 1920 - the names are all initials but the parents match up (assuming the Walter & Maud Megan marriage is correct). This family departed Liverpool on board the Corsican on 10 Sep 1920, bound for the port of Quebec:
W.J., age 34, labourer
M.L., age 34, wife
W.J., age 11
C.M., age 8
L.M., age 4
H.J., age 3/12
Did your father have any siblings and if so do they match up with these initials? Using these ages, I searched for the parent's births and found a Maud Louise Megan, birth registered in Pancras in Dec 1887 Vol 1b Page 48. This led to a census find in 1891 (RG12 Piece 218 Folio 73 Page 78) at 21 New North Street in Holborn:
John Megan, age 36, born Strand London, occupation House painter
Mary C, age 35, wife, born Strand London
Ada M, age 10, born Holborn
Edith E, age 9, born Holborn
Rosina, age 7, born St Pancras
Maud Louisa, age 4, born St Pancras
Florence May, age 1, born St Pancras
By 1901, John Megan had died (possible match in Dec 1899, St Pancras Vol1b Page 15, age 44yrs) and Mary was a widow living with three daughters - Edith, Maud and Florence - at The Bells Dwellings, 178 Drury Lane in Holborn (RG13 Piece 238 Folio 51 Page 33). Their occupations are all listed as Flower Seller.
There are a few possible matches for Walter John, in Berkshire and Oxfordshire - do you have any idea where in England he was born? Did he die in Canada, if so where? His death registration might contain his place of birth which would narrow the search.
Regards,
Lynwen