Wendy,
Thanks very much for looking all this up for me...
I think you've almost certainly unearthed Emily's parents' wedding there, but John MILLS was, according to both the 1851 and 1861 a "Cotton Warp Sizer" - have to admit that I have no idea what sort of job that was, but I'm sure some knowledgeable person on here will tell me before long. He employed 8 men in 1851 and 9 men in 1871, so he probably liked to keep his business concerns manageable.
But those children you mention in the 1851 Census certainly tally with the later ones, so perhaps he changed his occupation some time in the next 10 years - quite possible, I suppose.
Hadn't realised that Emily might have already been born by 1851, surely if it's stated that she was 11 months old, that would pinpoint her birth year as 1850...
All very interesting, if a bit confusing!
Very many thanks,
keith