frances wrote:He was dead at the time of Davina's marriage in 1922.

I hope that is a typo and she did not marry at age 12
In any case, I thought I had tracked him down (pouring rain outside and I'm sitting here in a 8x12ft cabin going stir-crazy, so you're doing me a favor

) but then none of the possible-looking deaths in Edinburgh from 1909-1937 seem to be him. So perhaps he went elsewhere. With such a common name, it's hard to find him.
Anyway, here is the one I decided to follow:
He was supposed to be 34 in 1901 as given in my first post.
Then I'm guessing he's this one in 1891, although a few years older:
1891
53 Blackfriar's St, Edinburgh Iron Church, Canongate, Midlothian
Francis Mitchell, 35, Head, born Edinburgh, General Labourer
Sarah Mitchell, 34, Wife, born Newport, Fife
William, 14, Son, born Edinburgh, Billiard Maker
Francis, 11, Son, born Greenock, scholar
Jessie, 6, Daur, born Greenock, scholar
Bessie, 5, Daur, born Greenock
Sarah, 3, Daur, born Edinburgh
Helen, 1, Daur, born Edinburgh
James Mitchell, 27, Brother, born Edinburgh, Stableman
This is the same James in 1881, trying his hand at being a butcher, but it didn't last (brother Robert changed occupations too):
1881
Edinburgh St George
William Mitchell, 42, Head, born Edinburgh, Venetial Blind Maker
Elizabeth, 44, Wife, born Edinburgh
Robert, 19, Son, born Edinburgh, Butcher
James, 17, Son, born Edinburgh, Butcher
Here they all are together in 1871:
1871
Leggates Land 3 B, Edinburgh St Cuthberts
William Mitchell, 32, Head, born Edinburgh, Venetian Blind Maker ("Venetian Blond Makor")
Elizabeth, 38, Wife, born Edinburgh, Blond Makeis Wife
Francis, 15, Son, born Edinburgh, Apprentice Joiner
Rolert, 9, Son, born Ab, Scholar
James, 7, Son, born Edinburgh, Scholar
Lizzie, 2, Daughter, born Edinburgh
Francis was also a venetian blind maker in 1881 in Greenock.
William Mitchell & Elizabeth Cavers married 4 Jul 1860 Edinburgh Parish (IGI)
Children of William Mitchell & Elizabeth Cavers all born Edinburgh Parish:
Robert William born 4 May 1861
James David born 15 Dec 1863
Lizzie Lindsay born 6 Jan 1869
Elizabeth Mitchell other surname Cavers died in Edinburgh in 1890
So, I'm reasonably sure I have the same family from 1871-1891, but then the jump to the groom in 1901 and then onto fathering Davina needs more support. If David was his second name (as in the birth record,) then that might explain the name Davina.
I wish I could find his death, but so far have not found the death of a James who has parents William Mitchell and Elizabeth Cavers, nor any James who is a groom
And the rain is letting up so I'd better go do something else....
Cheers,
Sarah