I just looked at the Renfrewshire Greenock Parish 1841 Census.
There are no Manners...but I think maybe this could be them.
As this JOhn is born in Ireland, could be the name changed.
And he is the only one of the page with JOhn - Catherine combination.
Volume 23. Page 3.
Address: Harvey Lane, ST.Thomas, Greenock.
Name: MANALUS.
John. HD. age 30. Labourer. Born Ireland.
Catherine. HM Age 25. Born Ireland.
Samuel. HD. Age 25. Labourer. Born Ireland.
Catherine. HM Age 20. Born Ireland.
JOhn. HM. Age 6. Born RFW
Henry HM AGe 3. Born RFW
John HM AGe 2. Born RFW
Nancy HM Age 1. Born RFW.
Susanna HM Age 1. Born RFW
Agnes HM Age 20. IND. Born IReland.
Don't know what the Ind. stands for in occupation.
I also know that when the Irish came to Greenock their names were Anglicized.
Maybe it would be worth your while emailing Watt Library ..Greenock for the rest of the census. They are very
helpful...just state you are from abroad...gets done quicker.
http://www.scottishrecordsassociation.org/summaries_003.htm