The usual apologies if this is already posted, but I've been trying to hoover up some Muirs...

From 1891 Census
James R Roberts, Head, M, 31, Commission Agent Provision, Lancashire, Toxteth Park
Mary B Roberts, Wife, M, 29, London
John R H Roberts, Son, 3 mths, Lancashire, Toxteth Park
Gertrude E Muir, Sistyer-in-law, 18, Lancashire, Walton on the Hill
+ 1 servant
all at 51 Bryanston Road, Toxteth
Mary B would be Mary Barron Muir, and both she and Gertrude are sisters-in-law to Allan Robertson.
Now I've typed this, I'm sure I remember it being posted before. Time to get my coat again...
Paul