Denise, I had Elizabeth Todd's christening as 1850 - my mistake it should have been 1858. I also noticed that I had put down Lilias Grace & Alexander Todd's daughter as Lilli Grace and it should have been Lilli Eleanor 1884. When I looked again at the I.G.I. the marriage of William Todd & Grace McClure is registered 03 April 1825 in both Borgue, Kirkcudbright, Scotland and Penninghame, Wigtown, Scotland. I will be in Wigtown in about three weeks time and I'll see what I can find out there - unless you already have this information.
I also checked 1841 I.O.M. census
Ballaquayle
William Todd 41 gardener born Scotland
Grace Todd 45 Scotland
Margaret Todd 16 Scotland
Alexander Todd 14 Scotland
Lilias Todd 12 Scotland
William Todd 10 Scotland
Elizabeth Todd 8 Scotland
John Todd 6 born I.O.M.
Agnes Todd 4 born IO.M.
Marie Radcliffe