Spending a bit more time looking at it, I don't think this is the right person. I've matched this one up to a different census sheet, but your Miss Walker certainly only ever lived either in the Observatory or just next to it. I've drawn a bit of a blank, but I'll certainly keep an eye out for her.

That's a shame. She was one of the very first women to be employed in astronomy - and we're desperate to find a picture of her. Thank you so much for your help.