Question about item I suspect is railway related

[HC1998]

Hi guys, I found this lying around at home and wondered what it was. A quick google suggests it is railway related. On the front it has the letters 'TA' stamped on it and on the back, it says 'E'. Any ideas? There appears to be a slot cut out on one side.

pics: http://imgur.com/a/MtLFl

 

[pompeyfan]

Looks like a drivers key to me.

 

[HC1998]

Looks like a drivers key to me.

Thanks for the reply, any ideas on what the TA means?

 

[pompeyfan]

Thanks for the reply, any ideas on what the TA means?

I don't know, but an educated guess would lead me to think it might be a depot code or something along those lines.