Hi Bob,

This is certainly a tricky one! I couldn't find anything on the IGI showing those parents or an illegitimate son to Margaret Boyd, or a marriage between her and Robert Christian. You have probably already tried that yourself.

You said that Robert Christian was aged 26 in March 1874 in the passenger record to NZ, and these ages are usually pretty reliable compared to ages given when they are older, so if that was correct he was born c. 1847.

None of the census entries appeared to fit, or were not possible to identify because the Robert Christians were working for someone unrelated. - I found just one possibility in 1851.
In Ballacrop, German, there was a Head of Household Catharine Boyd, unmarried, aged 60, with Margaret Barr, sister, widow, aged 55, Wm Wade son-in-law mar., 24, farm labourer, Margt Wade, sister's ? law? mar., 27, milinor, and three nephews: Wm Currin 9, Robt Christian 4, Wm Wade 1, all born German.

William Wade and Margaret Barr married 28 Oct.1848 Kirk German. Their son William Wade (aged 1 in the census) was bapt William Caesar Wade in German on 15 Feb.1850.
Margaret Barr was bapt 14 Sept.1823 Kirk German daur of Robert Barr & Margt Boyd. Her parents married 13 Oct.1815 in Braddan.

The IGI has a bapt for Robert Barr 14 March 1847 Kirk German, mother Margt Barr. No father given (illegitimate). If his father was Robert Christian he would be known as Robert Christian in the Manx way, even if his parents never married.

The third, eldest, nephew William Currin, 9, appears to have been bapt 4 Feb.1842 Kirk German son of Wm Corrin & Margt Barr.

So Margaret Barr appears to be the link between these three (gt) nephews of Catherine Boyd, who were the grandchildren of Catherine's sister Margaret Boyd, the widow of Robert Barr.

If Robert Christian grew up with his gt aunt Catherine Boyd, and his grandmother Margaret Boyd or Barr, he might have thought that his mother's maiden name was Boyd? He was only a year old when his mother Margaret married William Wade.

Anyway, that's my best guess! Someone else might find something better in the censuses.

Sue