You may be on to something there re Harland & Wolff. When he died his occupation was still a Ship's Caulker. It could be he secured the job when he was in Glasgow - as i believe in these days they worked on contract, and then returned (with a wife and family in tow) to Glasgow after his contract ended.
His own father Dugald McFarlane had a sad time of it see below from a newspaper cutting
Glasgow Herald (Glasgow, Scotland), Friday, October 17, 1856
Melancholy Case of Suicide.—On Wednesday evening, about half-past five o'clock, a man named Dugald M'Farlane, a saw sharper to trade, and residing in Partick, committed suicide by leaping into the river about a mile below Partick. The act was observed by several labourers, who were at work in the vicinity, but before they could render any assistance, the unfortunate man had disappeared. The body was recovered in about ten minutes afterwards, but life was extinct. Deceased, who was in a desponding state of mind, consequent on the unsuccessful issue of a law case, has left a widow and six children, five of whom are unable to earn their livelihood.
There’s also an advert placed by Smith & Rodger, Middleton Iron Shipyard, Govan, in the Glasgow Herald, July 14, 1854, accusing a list of employees, including a Dugald McFarlane from 1st July, of deserting their employment. It warns other shipbuilders against employing them and there seems to be a threat of legal action if they do so. If this is your Dugald maybe it was a development of this that drove him to it.
James would have been about 10 when this happened and as far as i can make out he lived with his sister up to whenever he left for Belfast.
It's a pity there were no list of employees who worked for Harland available.
Thanks for the reply,