Hi Dorrie,
It looks as though the first use of Chatham was in 1852 in Edinburgh, my gtgtgdfather by now in Glasgow quickly following suit. Yet the George Chattie & Helen Gowans family tree, your line, went with Chattam initially, only to end up (after some to-ing and fro-ing) as Chatham as far as I can see. My records have George Chattie's death as 11-3-1858 rather than 16-3-1857 when twins Thomas & Alexander were born. Just to confuse things, Alexander's surname on his death on 17-7-1916 is given as Chatty - by his son who signed himself as R Chatty! Can you tell me down which of Alexander's nine children your husband descends?
I really don't know why the surname changed. Any theories?
Chatta, Chattah and Chatto have been used too. How the pronunciation evolved is also uncertain - Shatton/Shotton obviously start with a soft 'sh' as in 'shatter', yet certainly now Chatham and I expect Chattie as well as Chattam have a hard 'ch' as in 'chatter'. Yet, I was surprised to hear just recently a reference in a TV documentary by no less than Prince William to the Queen's niece Lady Sarah Chatto which he pronounced with a soft 'sh' - which threw a different light upon things. There were Chattos around Abercorn and indeed, and maybe because of this, Thomas Shatton is recorded as Thomas Chatto in 1797 Horse Tax records at Duntarvie, Abercorn. Makes one wonder whether Chattie is merely a diminuitive of Shatton, first being pronouced with a soft 'sh' which gradually evolved to a hard 'ch', I can only think the evolution to Chatham was for vanity reasons, maybe something to do with Chatham the dockyard or Sir William Pitt, 1st Earl of Chatham, with Chattam being simply a misspelt version bearing in mind Chatham is pronounced.
The origins of Shatton itself are mysterious. But there is a village in England, in Derbyshire, of that name, in the parish of Hope. Bearing in mind Thomas Shatton was on the Hopetoun estate, and there were several Thomas Shattons in Shatton, I thought I might have cracked it, except that Hope parish has nothing to do with the Hope family of Hopetoun - or does it?