I am to go

[englishhobby]

My friend has some friends from Britain. Recently he said to them 'I am to go'. They teased him a little for his old-fashioned English. Is this phrase really dated?

 

[Yankee]

Maybe dated, but I would hear/use it occasionally as in "I'm to go to the dentist tomorrow so I'll be late getting home."

 

[5jj]

Recently he said to them 'I am to go'.

In what context did he say this?

 

[englishhobby]

In what context did he say this?

He used it instead of 'I must go/I have to go' when he was going to leave.

 

[5jj]

In that case it's completely unnatural.

 

[teechar]

I agree that on its own it would be unnatural like that. However, note that "I'm to" can mean "I am supposed to/expected to/meant to". For example:

I'm to go shopping with the in-laws later on.
I'm to hand in that report by Friday noon at the latest.