Hi Ken
With everything that you have now (including the occupation for father Robert as labourer from that marriage cert in 1911) I think you are firming up that family of Robert and Margaret (Gold) for your Robert.
The problem with relying on census ages is that they can vary enormously. For example, if we do have the right entry for Robert in Sunderland a few months before his marriage in 1901, he showed as b. 1869, aged 32. His marriage a few months later,aged 34. Yet everything is currently pointing at that 1861 birth in Bathgate. Varying ages is very much a sign of these times.
Also, cannot see a death in Northumberland for a 60 yrs old Robert Stevenson/Stephenson to match an 1866 birth, just the one I posted first in 1927 for a 66 yrs old Robert. Have you checked on Freebmd, you will see what I mean.
You say it was noted he was 60 yrs old when he died, where was this?
Monica