In the 1901 census for England, Mary Ann Wright (nee Harper) was living in Kings Norton, Worcestershire (not Birmingham) with her husband Stanley and her children.
In the 1911 census she's shown as a widow (which was untrue -- see Finding an elusive ancestor after the 1901 census (who may have deserted his family)) boarding with some of her children with a Charles Kimmons at 1 Eton Road Balsall Heath, Worcestershire. Charles is shown as age 32 (also a widower) and she as age 40 (which is probably understated -- she seems to have been born around 1865 although I haven't found a birth record yet, but she was married in 1883).
So fair enough, she's found a place to board after her husband has moved on, and Charles Kimmons is her landlord.
In 1919 at his marriage, Mary Ann's son Bob is shown as resident at 49 Gough Street, Greet, Birmingham.
And in 1920 she's registered as a voter at 49 Gough Street, Greet, Birmingham. Also registered as voters there: Bob Wright and his wife Dorothy, and (!!) Charles Kimmons.
And she shows up at the same address in successive electoral rolls until 1930, with her son Bob and his wife (before they move out to Medley Road sometime between 1925 and 1927 when my father was born there). And every time Charles [William] Kimmons is listed on the electoral roll at the same address. She dies there in 1932 and the next trace of Charles Kimmons is on the electoral roll at Medley Road (but not the address where my father was born) in 1939, and then in the 1939 register at the same address, apparently a boarder. He continues to show up on the electoral registers at various addresses until 1955 and apparently dies in 1956.
Mary Ann is always shown as having an Occupational qualification to vote and Charles Kimmons is shown as having a Residential qualification.
It may be significant that Mary Ann always appears first in the electoral roll from 1920 -- but in every other entry I've looked at the property owner or (male) head of the household appears first.
One possibility is that Charles Kimmons moved house some time between 1911 and 1919 and she moved with her family, still as a Boarder.
Another possibility is that there was a less commercial relationship between them.
How likely is it that a family boarding in 1911 would move with their 'landlord' to another property?
Where else might I look to shed some light on the situation?
A potted history of Charles William Kimmons' life -- oh, the joy of an unusual name to research:
There's a civil birth registration that seems to be him in 1881 in Yardley, Birmingham, and the 1939 register shows him as having been born on 25 October 1881. There are militia/military records for him in 1900 (joining the Royal Warwickshire Regiment -- militia) and transferring full-time to the Royal Welsh Regiment in 1901 for 7 years (he states in 1901 that he isn't married). He was transferred to the Army Reserve in 1909 and discharged in 1913. He must have re-enlisted at some point as he has a medal card for service in France from 1/1/18 with the YMCA corps. According to the electoral rolls -- as above -- he's resident at various addresses in Birmingham from 1920 to 1955 and there's a civil death registration which is probably his in 1956).
I have not found a marriage for him in the Civil Registration indices for England and Wales -- the marriage in 1898 of Charles William Kimmins to a Grace Thirza is not his. He may have married overseas (I don't have access to the relevant subscription services) or he may not have married at all and lied in the 1911 census that he was a widower.