In 1901 there's a likely Florence M Harvey in the right part of Warwickshire with her parents, William and Jane. Same family there in 1901.
Perhaps the "Bevan / Bevin Florence married died quite soon after the marriage - mining was a highly dangerous job, after all.
Or the "Bevan/Bevin" surname may have been given to a child born without the parents being married?
Or perhaps that marriage simply failed and she went off and re-married without the bother of a divorce? A divorce at that time and class would have been unusual, and expensive, and once she's married to Mr Howard, they seem to stay together. May the child William Henry have been given his father's surname for that reason?
Have we found a death that's likely for Mr Bevan/Bevin? Probably 1905 - 1909 period?