Looking for Michael Shaughnessy

Michael is the father of my great, great grandfather Patrick Shaughnessy. This is the information I have;

1867 Marriage

To Mary Kennedy- 23 Jan 1867-the Catholic Chapel, Newcastle under Lyme, Staffordshire, England, his age shown as 21 on certificate, her age 24

His father Michael Shaughnessy labourer, her father Michael Kennedy labourer, Witnesses John McGrath and Bridget Kennedy, all parties signed X

This is the only reference I can find for Michael Shaughnessy. 

English marriage records sometimes have the fathers listed as deceased I don’t know if this is common or not, or whether if it doesn’t say deceased it safe to say the father is still alive, probably not.

1871 England Census-Patrick age given as 26, 66 Fletcher Street, Newcastle under Lyme, place of birth given as Ireland, also includes his wife Mary age given as 25, daughter Mary Ann age 3 and son John age 1

I also have all the English censuses to 1911, they all have his birthplace as Ireland, in addition the 1911 census has Galway as place of birth. There are additional children Margaret/Bridget, Catherine, Ellen and Elizabeth. I wondered as he named his only son John whether John was a grandfather or perhaps uncle.

I have looked for both Patrick and Michael on the 1851 and 1861 censuses and have not found anything useful-there are records of Shaughnessys in Liverpool and Manchester-I haven't found anything that connects them to the Newcastle family. So I don't know when Patrick went to England and I don't know if he went alone or with other family members.There are other Shaughnessy families in Newcastle under Lyme. it seems unlikely to me that he was the only member of the family to leave Ireland. I also know that no records were kept of people leaving Ireland for England. The first confirmed record is the marriage. 

I searched all the available Galway baptism records on Roots Ireland and found only 2 records of a Patrick Shaughnessy with Michael as his father in the 1840's. One record is for January 1846 in Dunmore, Mary Blake or Blakeny as the mother, the address is given as Slieve. The second record is for September 1841 Ardrahan with Bridget Grealy as mother. The 1846 baptism fits with an age of 21 at his marriage in 1867. 

I have since looked at the new release of Catholic Records from the NLI for Dunmore, there are lots of baptisms with Shaughnessys many Johns, Michaels, Marys and Patricks involved as parents or sponsors, and if my identification of Slieve as birthplace is accurate, siblings, Mary born 1834, Judith born 1836, and Eleanor born 1842.

I have also looked at all the Griffith Valuations for Michael Shaughnessys in Galway, there are records for Michaels, and Johns in the Dunmore area. There are Shaughnessy records with appropriate Christian names for other parts of Galway, includng Ardrahan, Ballylara and Caherglassaun.

Has anyone got any ideas for next steps? I am in Canada, so on site research is not possible. Are there areas where baptism records just don't exist. In which case I could easily be completely wrong.

If anyone can help I would be thrilled, and my 86 yr old mother who was brought up by her grandmother Patrick's daughter Mary Ann, after her own mother died very young would be even more thrilled!

Thanks in advance

Monica