Hi Louise, Hi Heywood!!
This is such an intriguing tale; I'll be almost sorry to see it solved, if we ever do track Robert's parents! Can't wait to update my Dad tomorrow he really won't believe this he was agog at the last lot of info and this is something else!
The puzzling thing about the 1822/1824 date is it really could be either. On the one hand the census ages kind of go down the middle, the Bastardy order is for a child born 5/4/ 1824 and we have a Christening from parish records for 13/12/1822. The latter two are irrefutable. We don't know the name of the child in the former, only that the mother is Hannah Fishwick, and it is Charnock Richard not Chorley. The Christening is a Robert, no father named and mother Hannah Fishwick, in Chorley!
Looking at the census ages these don't altogether tie up with either date i.e.
If Dec 1822 it should be, from 1851 on, 28, 38,48,58.
If 5/4/1824 it should be 26, 36,46 and 56. What have we actually got? Would you believe 28, 37,47,57!
At Robert's marriage to Mary Lee on 8/2/1846 he was 23 which ties up with Dec 1822. He would only have been 21 had it been 5/4/ 1824.
At his death on 2/4/1890 he is 66. Our dates would have made him either 67 or 65 almost 66!
Will have to ponder on this ... I'd really like to find the answer. Hope it's not staring us in the face!!

Who is Winifred Fishwick, buried in Robert's grave? Did she belong to Robert junior, your great grandfather? I note the maiden name on the Birth Index is Grundy so she presumably was either Robert's or James' child.
Ann Mann, where my story started! Ann married my Great grandfather William Halliwell in Chorley in September 1893. They had three children, William Edward, my Grandad, born 1894 in Chorley, Fanny, also born in Chorley, in 1896 and Louisa Hannah born in Blackburn in 1905. Fanny and Louisa never married and remained childless. William Edward married Ada Cassidy and had two children, my Dad born in 1932 in Blackburn and a daughter Edith born 1934 who lived only a few weeks. Ann died in Q3 of 1932 in Blackburn age 67. Your Mum might have a recollection of some of the family but whether or not she ever met Ann Mann?! My Dad's side of the family all hailed from the Chorley, Euxton and Blackburn areas and there appear to have been any number of cousins, aunts and uncles.
I don't know whether Betsy Fishwick (nee Bradley) ever knew about Ann Mann. If so, when Ann's Mum died in 1866, why didn't Ann go to live with her Dad Robert and Betsy and all the other children including Elizabeth from his first marriage? Instead she lived with Robert's half sister Ann Morrison (nee Rodgett, daughter of Hannah Fishwick and Thomas Rodgett). I think the 'sleepover' with Alice Mann must have been kept a closely guarded secret only to be unearthed by us 140 years later!
Have a lovely weekend

Lyn
Here's a photo of Ann, William and the 3 children william Edward, Fanny and Louisa Hannah. Taken about 1907.