Hi Mable
No doubt you'll have all the following - but it may help to see it, to track him down pre-marriage and/or with parents

This must be the Alexander SWANSON, with wife Ellen in the English Census? He was a Nurseryman/Florist
1871: Barton, Glanford Brigg, Linclolnshire
Alexander is 33, b Scotland with wife & children. He is a Nurseryman
RG10/ Piece: 3438/ Folio: 55/ Page: 41/
1881: Barton, Glanford Brigg, Linclolnshire
Alexander is 43, b Forres with wife & children. He is a Nurseryman.
RG11/ Piece: 3291/ Folio: 68/ Page: 49
1891: Barton on Humber, Glanford Brigg, Linclolnshire
Alexander is 53, b Scotland with wife & children. He is a Florist.
RG12/ Piece: 2630/ Folio 106/ Page 21
1901: Sutton Without, Sculcoates, Yorkshire
Alexander is 60, b Banff with wife and a daughter named as Mary E age 33 single. he is a retired Florist.
The daughter is likely to be Margaret Ellen b 1867(perhaps written as Marg. Ellen on House schedule and enumerator mis-read it?)
Chidren: all registered Glanford Brigg, as SWANSON - and appear on the Census with parents (except the two who died)
John Marshall b 1865,
Margaret Ellen 1867
Sarah Ann 1869,
Alexander James 1871,
William Henry 1873,
Harriet Elizabeth 1875, (on 1881 as Elizabeth)
Richard Marshall 1877 (died 1877)
Mary Jane 1878 (died 1878)
George Donald 1882
The children may be important for establish a Scottish naming pattern if possible.
I think there was some boundary changes for Elgin, Moray, Banff? which may account for the difference in pob 1901 and 1881.
http://www.undiscoveredscotland.co.uk/usfeatures/areas/moray.htmlhttp://www.genuki.org.uk/big/sct/MOR/All this indicates :
the correct name is SWANSON
Cheers
AMBLY