Although nobody has yet responded whether they think the Johnsons I found in 1861 are Charles wife Alice, it seems as though it could well be the family, so I'll be trying to continue these through 1881-1901 and see what we come up with.
Mary - I hoped someone else might have an opinion on this, seeing I was the one who suggested it might be a second marriage, so I'm possibly prejudiced! But you certainly convince me. Let's put the 2 families together for the sake of those who haven't followed this line:
1861 censusCharles Mackae Robertson 27, b. Limehouse.
Unmarried, living with his motherIn a completely different household, Mary found:
Alice Johnson Wife Mar 23, b. Liverpool
no husband listedCharles Johnson Son 3, b. Liverpool
Jessie Johnson daur 2, b. Liverpool
Alice M Johnson 6 months, b. Stepney
1871 censusCharles M Robertson Head Mar 47 b. London Sailmaker
Alice Robertson Wife Mar 47 b. Liverpool
Charles M Robertson Son 18 b. Liverpool
Jessie Robertson Dau 17 b. Liverpool
Alice M Robertson Dau 14 b. Stepney
Helen E Robertson Dau 10 b. Stepney
Agnes M Robertson Dau 8 b. Hertfordshire
Lilias Robertson Dau 5 b. Stratford.
Although the ages vary a bit, I don't think there's any doubt it's the same family.
Helen E is probably the Ellen Emily Robertson christened by Charles Robertson and Alice in Stepney on 15 May 1864. (IGI)
According to the IGI, Charles McCrae Robertson (sic) and Alice had a son Hugh Moody Robertson in Stepney on 29 Mar 1869. Perhaps he died young, because he doesn't seem to show up on the 1871 census - although I'm willing to be proved wrong!
For completeness, I will add that Mary has found 4 of the children in 1881, but no sign of Charles and Alice:
At a school in Hampshire, Alice Robertson (20) b. London, is assistant matron. Helen Robertson (17), b. London and Agnes Robertson (14) b. Bushey, Herts, are scholars.
Lilias Robertson (13) b. London is at a different school in Cheshire.
NB The ages given in 1881 fit better with 1861 than 1871 - I don't think Charles knew how old his step-chidren were!OK: I'm going to enter all this in my software - back shortly.
Rambler