@patchysmum There's a very big clue contained in the census. If you have a look at the "Completed years the present marriage has lasted" column then you will see it says "2".
So they had been married for two years but the children are between the ages of 4 and 14.
If you search for marriage records two years previously you will see that William Henry Holroyd did indeed marry Jessie Smith in Q3 of 1909 in Hunslet, Yorkshire. If you are really interested then you can get a copy of the marriage certificate from the General Register Office.
You will then notice that the youngest son is given the surname of the man as a middle name (Holroyd). This was not uncommon when the parents were unmarried.
Indeed, if you look at the birth records for him it shows that he was born in Hunslet in 1907 but there is no mother's maiden name given. When this happens (or occasionally if the maiden name given is the same as the last name of the child) this generally indicates that the parents were unmarried.
I think it likely that George was the son of William and Jessie, but William wasn't the father of the older children.
So, if you then turn to the older children, James, Clifford and Harold. Unfortunately, Smith is a very common name but there are records of a James, Clifford and Harold being born in Hunstal in the correct years and the records all show the same mother's maiden name - Chappell.
The next step is to see who the parents (Smith and Chappell) might have been. Well, it turns out that a Jessie Chappell married Arthur Smith in 1894 in Hunslet. I think this is likely them as the oldest child, James, was born in 1897.
So what happened to Arthur? Well, there is a record of an Arthur Smith dying in Hunslet in 1905 aged 34, so he would have been born in 1871. I think this is likely the correct Arthur as Jessie was then 30 and had been born in 1876. Also, their youngest son was born in 1904.
So it would appear that Jessie first married Arthur Smith and they had three sons together. He then died in 1905 and she subsequently began a relationship with William Holroyd and she got pregnant sometime around May or June 1906.
I think that Jessie (or Jessica) may be a middle name, as although she appears on the earlier censuses I cannot find any record of her birth.
I have also attached a copy of the 1921 census which shows that they had a further son together in 1912 who was called John Holroyd. The 1921 census contains quite a bit of extra information. If you have trouble reading any of it just let me know.
In 1921 they were living at 13 Brewery Yard, Hunslet. William was a boiler rivetter and the sons were out of work coal miners.
The houses seem to have since been knocked down but were behind the Blooming Rose pub on Burton Row. Here is a photo:
https://www.facebook.com/groups/252700481779889/posts/1713602815689641/