There is a Mary Mallard in Ira's will and I am assuming it is her but cant find a marriage.

1891
Ira James abt 1817 Bream Eaves, Gloucestershire, England Head West Dean, Gloucestershire
Ann James abt 1815 Pellowell, Gloucestershire, England Wife West Dean, Gloucestershire
Mary J James abt 1886 In France Foundling West Dean, Gloucestershire

If Ira dies in 1898 - this would make Mary "James" approx 13 at the time - possible to be the Mary Mallard but a little young to have married.

a long shot is an 18 yr old.
1901
Mary Mallard abt 1883 Lydney, Gloucestershire, England Servant Lydney, Monmouthshire

1891
Charles Mallard abt 1856 Lydney, Gloucestershire, England Head Lydney, Gloucestershire
Celia Mallard abt 1856 St Metons, Monmouthshire, Wales Wife Lydney, Gloucestershire
Mary C Mallard abt 1883 Lydney, Gloucestershire, England Daughter Lydney, Gloucestershire
Ada G Mallard abt 1885 Lydney, Gloucestershire, England Daughter Lydney, Gloucestershire
Charles W Mallard abt 1887 Lydney, Gloucestershire, England Son Lydney, Gloucestershire
Wallace H Mallard abt 1889 Lydney, Gloucestershire, England Son Lydney, Gloucestershire
Elsie A Mallard abt 1890 Lydney, Gloucestershire, England Daughter Lydney, Gloucestershire

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Ἀριστοτέλης A Gloster & Hereford Boy in the Forest of Dean ><((((*>

There are a few Mallard's on various census born in France e.g.

1901 Census, Leicestershire

Claire MALLARD, age 38, Ladies Maid, born France, Villier Sur Tille

1891 Census, Sussex, Hove

Alex MALLARD, age 25, Porter, born France

Also the name appears to sometimes be spelt Maillard -

Marriage of a Mary MAILLARD, O/N/D Qtr 1920 Swansea ? to CROSSMAN

I think there appears to be a strong link between France and the FOD area. One of my ancestors is reputed to have been French but I can't find any documentary evidence of it. It was very much earlier on than this though.
However, another branch of my family, not FOD in origin though, had people born and living in France. I couldn't understand it and then found they have been living there because they were engineers connected with building the railways both here and in Paris. So, sometimes the links are different from how you might imagine and very interesting. Another branch of my family has members born all over the place and again it made sense when I found out that their fathers were vicars or in the army, posted all over the world for their work. One of the vicars set up a number of orphanages so it's worth checking whether your family might have some connection like this e.g. did they work in an orphanage there and adopt one of the children? Just some ideas but hope they help.