Out of interest I did a speculative search on the newspaper archive for Railtons in Blackburn and found the following deaths.
Blackburn Standard 2 March 1836 " On the 19th ult,after a long and severe illness,Mrs ? Railton,wife of Mr Robert Railton, sen, machine maker, of the firm of Messrs Robert Railton,Sons and Co.,Union Foundry, Salford.
(Have put a ? against her first name as there is a bend in the paper but the more I have looked at it I think it says Osith).
Preston Chronicle 7 April 1838 " Same day (saturday last) Elizabeth, wife of James Railton, Cleaver Street, Blackburn, aged 24 years.
Preston Chronicle 7 Dec 1844 " Yesterday week in his 82nd year, Mr Robert Railton, engineer, Blackburn".
There are further articles in the Blackburn Standard 11 June 1856 and 8 April 1857 which refer to the inventions of Robert Railton in improving cotton spinning machinery. These articles, and others, would also suggest that the Robert Railton showing in the 1841 and 1851 census born 1787 was his son. (The 1851 census gives his place of birth as Brunton on Swale, Yorkshire - he died 1860 and there are letters of administration for him). I also suspect that there was another son Ralph born in Yorkshire(an account of his death is in the Lancaster Gazette 23 Feb 1828).
There is also a piece in Perry's Bankrupt Gazette regarding the dissolution of a partnership ( a James Railton is referred to) which is worth a look.
If the marriage cert you have sent for does indeed show that Robert Railton was James's father you really do have a most interesting family in terms of our industrial heritage.
William