Hi,
I have looked up on the Later Day Saints site , and it is only a submitted records that gives birth 1742 death 1818, no parents names.
I then looked under Scotland Peoples website and there is no birth/christening record for a William Preston in 1742, however there are 3 christenings in Midlothian between 1734 and 1765.
c 02 Feb 1734 to Alexander Preston & Isabel Clark
c 08 Nov 1737 to William Preston & Janet Gray
c 22 Sep 1765 to William Preston & Elizabeth Brown
I have had a search on some of the articles about William but he does not mention his parents by name only that his father was a Writer to the Signet. I then looked up Wills on Scotland People website and there are 2 WS died between 1750 and 1800
1 Preston William 14/11/1752 W.S., resindenter in Linlithgow TD and Inventory Edinburgh Commissary Court CC8/8/114
2 Preston Alexander 14/05/1776 W.S. TD Edinburgh Commissary Court CC8/8/123
His father died before 1760 as he decided to leave college and get a job with Thomas Ruddiman.
So his parents must be William Preston and Linda Gray, and he was christened at Inveresk parish near Musselburgh, Midlothian, and christening date is 08 Nov 1737
Tom