Where do I put my C# delegate declaration, in a file of its own?

Out of habit I tend to put classes/structs/enumerations in separate files when not nested.

For delegates, it seems like overkill to create a seperate file for a one liner:

public delegate string MyDelegateThatIsNotNestedInAnyClass ( string par );

I usually add it to the bottom of the most closely related class file. I was just wondering what other people do?