Hi Clazey,
I can not find any reference to Alexander Tough but
I have found some Keith's in the Aberdeen Obituaries (1840-1854) booklet that I have but do not know if they will fit in with yours. There are;
Keith 8th July 1854. At the Free Church Manse, Strichen, the infant son of the Reverand Alexander Keith.
Mrs Keith, 10th September 1847 at Motimer House, Clevedon. The widow of Alexander Keith, of Ravelston and Dunotter.
James Keith 27th January 1851 at 101 Crown Place East, of the Hudson's Bay Company, aged 68.
James Keith 22nd February 1851 at 1 Crown Place East surgeon, Royal Navy aged 76.
hope that this is of some help
old rowley