What does it mean?

[Gadget]

I assume that's his father, Neale.

Is there any sign of William B's  mother or sister Mary?

[softly softly]

May be~

1881 Census
Cornwall Street,  Govan
William B Buchanan. 41, Shoemaker, b. Edinburgh
Charlotte B Buchanan, 37, b. Ireland
and 5 children  -  under 2 - 11, b. Ireland, England and Glasgow

Gadget

Possible birth of child in England?

BUCHANAN, EMILY       mmn BELL 
GRO Reference: 1875  S Quarter in PORTSEA ISLAND  Volume 02B  Page 428

SS

[Gadget]

Looks like it SS

The list of children in 1881

Thomas B. 11,  b. Ireland
Mary Ann,  9  b,  Ireland
Emily B, 5, b. England
Alice B, 3, b Glasgow
Ellen B. 8 mths, b. Glasgow

Gadget

[softly softly]

Charlotte's first marriage.

https://civilrecords.irishgenealogy.ie/churchrecords/images/marriage_returns/marriages_1869/11410/8190342.pdf

SS

[Gadget]

I was just about to give that 

Charlotte Bell married John Reilly on 31 January 1869, Dublin North
John was a shoemaker also.

Add - I think the OP said that he knew about Charlotte though. He wanted to know about William B)

[BushInn1746]

I think I am confused.
 From a search on Scotlands' People
  I was looking for death of Charlotte Buchanan, nee Bell in 1918, married to         
  William Bain Buchanan, and got this (correct details in all aspects but....}
  "Charlotte Bain
 formerly Buchanan
 Widower of 1st John Reilley, bootmaker
 2nd William Buchanan
 formerly Bain, Private 2nd battalion
 Royal Scots Fusileers"

  Can anyone explain what this this is telling me please
  Did he or she alter their surname with middle?

  (I do get the 1st widower bit)

  Cheers

Yes, Charlotte Bell, has married (or been the wife of) twice.

Added:
First to Reilley
Secondly to Buchanan a.k.a. Bain

It would also appear from Gadget's reply at 6 with the death details of William Bain Buchanan also calls him, or says he was known as William Bain (his mother's family name).

See Gadget's reply 6 (and Wife 2).
https://www.rootschat.com/forum/index.php?topic=879966.msg7523173#msg7523173

So that is how you end up with Charlotte Bain (or Buchanan), looking at the death details of both.

Your Certificate is also acknowledging any alias or 'also known as' names for Buchanan.

As you build up your tree with Certificates / Census, hopefully it should all fit together nicely.

Added:

Many years ago I went through the 12 or 13 Memorial Inscriptions Volumes (set out in surname order) for all the churches of S.W. Scotland and there was also a lot of using the mother's or nee name on the stone and underneath 'the Wife of' ... Added: or on Family graves, to show lineage / descent.

A few might also have lived together as a husband and wife and/or formally married later.

[softly softly]

Names of Charlotte Bell & John Reilly's parents

[Gadget]

The nearest that I can find for sister Mary is:

1881
B Back Land
39 Crown Street, Govan
Isabella  McInarny, wid, 56, b. Ireland
Peter, s, 37, unm, fruit salesman, b. Glasgow
Mary, d, unm, 35, Cotton piecer, b. Glasgow

Could she be Charlotte's sister  rather than William's ??

Gadget

[Gadget]

Note that on Charlotte's death certificate, the informant was Thomas Reilly . Son .  I presume this was the Thomas B listed  on the 1881 b. Ireland. My Reply #11 above.


Gadget