You have a mother named Francis in 1861, but I've no idea how you identified that particular family.
In 1861 you have his age at 9 - it MAY have been transcribed as 19, but if so then the transcriber has mistaken a mark written afterwards, probably when numbers on the page were being counted.
In 1881 you have his age at 32
In 1891 you have his age at 38
If I look at 1871 I have a couple of possibles
One is aged 19, a bricklayer born Carlisle and Boarding with George and Eliza Hart in Whitworth, Durham.
Another is already living in Middlesbrough which suggest that he might have moved there with his family quite a while before getting married - if it is him.
Pandin? Place, Middlesbrough, Durham
Christopher Morrell Head Mar 48 Labourer Stockton Durham
Margaret Wife M 44 Carlisle Cumberland
Robert Bell son Unm 21 Carpenter Carlisle Cumberland
George Bell son Unm 18 Labourer Carlisle Cumberland
Margaret daur 14 Scholar Carlisle Cumberland
Leonid Morrell son 11 Scholar Middlesbro Yorkshire
RG10; Piece: 4892; Folio: 31; Page: 55
AND this Robert is a carpenter which fits well with his occupation in 1881, also did he like his stepfather enough to name his first son after him?
So you see I could make quite a number of Robert Bells fit the facts of Carlisle and age - I haven't even spread the net as far as areas within Carlisle, such as the Wigtown entry you have in 1861. There are Roberts born Carlisle living in St Andrew Holborn, London, or Ramsgate Kent and then others born Kirklinton, Acreheads, Bolton or Gilcrux, all in the Carlisle area.
I don't wish to wet blanket your find but I just wanted to show that you need more evidence than a birthplace. You NEED those certificates.