RootsChat.Com

As a rule of thumb,  in the 19th century or before,  expect no standardisation at all. So McD, MacD, M'D, MackD are likely to show up anywhere. And Donald or Donal or any other wobbly spelling.
I'm working on a transcription project at the moment and the variety of spellings is endless. 
With much higher literacy rates in the 20th century there is rather more consistency.
And yes, I'm aware that this doesn't help!

Try Crockfords Clerical Directories - available on Ancestry. This will list any Church of England clergy.

If he was an army chaplain he might be in the Army List of the time.

Here's some guidance....
https://www.nationalarchives.gov.uk/help-with-your-research/research-guides/passports/

I've also been wondering if this isn't quite correct. The Chancellor of the Exchequer is a politician, not a judge, and isn't (such is the way of things) linked to the Court of Chancery, which is where such issues would have been litigated.
Rather differently, I have memoirs from my great-aunt who claimed that her grandfather owned most of Cheapside in the City of London in the late 18th century. Those memoirs, written in the 1970s, are often correct but often not so; the only thing I can find about this City figure is that he was in a debtors' prison! A distant cousin placed lots of adverts in newspapers of the late 19th century selling shares in goldfields in Australia and India; these appear to have been fraudulent and the printed version of the phone calls we now get from scammers claiming to be Microsoft, or 'your broadband company,' or whatever.