Hello Alex. I think you're a bit mixed-up between your Harrys and Davids and Williams! I'm Harry, and it was William (not David) Spink who married Mgt. Turnbull.
The inscription on their headstone in Arbroath Abbey churchyard reads as follows, in the abbreviated form used in the Scottish Genealogy Society volume -
1847. Wm Spink 9.7. 1857, 75, w Margt Turnbull 17.6.1839 59, s Thos 24.11.1835 26, da Jessie 2.1836 16, da Margt 9.2. 1855 39, s Jas 19.8.1864 47, da Mary d Arbroath 13.8. 1880, 57, by s Wm lightkeeper 27.8.1889 80 (2w Janet Adair 21.10. 1877 65, da Mary McCrackan 16.10. 1853 5.8. 1858, 1 w Sarah Anson 20.3. 1847 33).
When William Spink(Turnbull) died in 1857, his death was registered by his son James, and it was James who said his father was 75, and that his parents had been James Spink and Helen Smith. This latter couple are recorded in the St. Vigeans OPRs as resident in Auchmithie.
I've found Margaret Turnbull's death in the Arbroath OPR for 1839, and it confirms that she was 59.
I don't think we are allowed to include attachments with our posts here, so if you want to send me a private message with your home email address, I will send them on to you that way.
It's possible, though not certain, that your James Spink who married Helen Smith is the James born at Auchmithie in 1742 to James Spink and Margaret Cargill. In that case, he was a brother of not one but two of my own ancestors - David Spink and John Spink.
I also had ancestors in Arbroath called Milne, which is the same name as your Mill, as in Bella Mill (local pronunciation and spelling of Milne).
Harry