Update on my SENNETT/SINNOTTs, having just come back from Ireland and a successful visit to the Dublin National Library genealogy room. Note that spellings all vary and seem a bit interchangeable, and these all took on the spelling SENNETT once in England.
Joseph SINNOTT/SYNNOTT and Julia RYAN had four children baptised Temple Rainy Chapel (Avoca Parish) in the early 1840's prior to leaving Ireland for Whitwood, Yorkshire in about 1847/48. (Only two of these survived until the 1851 census, but unsure at this stage if they died in Ireland or Yorkshire).
Not 100 percent confirmed, but highly likely is that Joseph was born and baptised in Castlemacadam (COI), along with at least two siblings. It would seem that this family became catholic with Joseph converting when he married Julia.
Also James SINNOTT who married Martha WHITE (and also ended up in Whitwood, Yorkshire) had most of his children baptised in Castlemacadam parish.
I did pick up quite a lot of other references to SINNOTT/SYNNOTT in Co. Wicklow, and particularly in the Arklow/Rathdrum/Wicklow area so when I can get time to have another look at them I'll check if any relate to any other messages on this thread.
Interestingly on my trip to Ireland I ended up staying at a B & B slap bang in the middle of Avoca Parish and within a couple of miles of where my family came from - totally coincidentally. It was the landlady who told me how to find Temple Rainy chapel.
Also interesting to me is that rather than Joseph coming to england as an unskilled labourer, it would appear that he was likely to be a highly experienced miner - coming from the Avoca copper mines.