You would have been right in a way a-l. It looks as if Alice Sutton was actually Alice Eliza and became the Mrs Gale that Mabel gave as her aunt. The fact that her son married an Eliza and it was that Eliza and the son who were witnesses threw me.
That's what is so great about RC, there is always someone who can work things out.
Thank you everyone who helped sort out this puzzle.