Identification of cap badge

i am trying to identify the regiment in this world war I photograph. I have another photograph of the same regiment with my ancestor John lamb seated but it is not as easy to make out the cap badge. Can anyone help?
Thanks david.

 

Hard to tell as the image is small. It appears it might be the Machine Gun Corps maybe?

 

I agree.
That emblem is the same as the one on their hates.
Boy I love old pictures though. Its like being in a time machine.