Homework help please - Thomas' coat or Thomas's coat?

[MrsFogi]

I must admit I am stumped on this one - dc is not sure, nor am I and I am getting conflicting answers on the net. But I know the Pedants of mn will know The Answer .

The Economist says Thomas's. I learnt that you can use either as long as you are consistent!

Pretty sure both are correct, but personally prefer Thomas'.

whichever you prefer, my surname ends with S so have given this one some thought. consistency is the key.

I thought that usually with one s it's s' and with two it's ss's unless it's a proper noun, like Thomas, in which case it's s's.

Both are correct. I think in Eats Shoots and Leaves she says the s' is for famous names e.g. for the Bible Thomas it should be Thomas' not Thomas's.

I'd do it the way you say it -- so Thomas's.

I'm an editor, and even our style guide refuses to commit itself. It just says "Please specify whether you have used James' or James's' throughout."

Thomas's.