I have Stowell Kenyon's book.

William Henry married Harriet Amelia Buttery and had 7 children:
Augusta Victoria m. Dr Donald MacDonald
Florence Edith ObSP
Margaret
Dora Gill m. H Radcliffe
Leonard m. Dorothy Gertrude Hill, moved to South Africa and had:
.....Dorothy Gertrude ObSP
.....John Finlo married but issue not traced by Stowell
.....Barbara Hilda Margaret m. Abraham Yonker
Stephen m. Alison Hewitt, moved to New Milton, Hants and had:
.....Marcia Corlett unmarried
.....Alison Ursula Finlo ObSP
.....Joan Hewitt changed her name by deed-poll to Stevenson and had:
..........Gillian Rosemary Stevenson m. Flavio di Vito in Canada and had:
...............Alison Louisa di Vito
...............Adriana di Vito
Beatrice Kate ObSP m. Algernon Mutrie Shepherd

There are quite a number of dates in the book which I can supply if required.

As you can see, the only possibility of a person named Gill being extant from this line is the untraced possible issue of John Finlo Gill in South Africa