Viewing attachments in email - cannot return to mail

I am a Mac and iPhone user but a newbee to the iPad. When opening an attachment from the standard iPad email application the attachment opens fine but there does not appear to be a DONE or BACK button to return to the mail.. Am I missing something? I am having to reboot the machine to get back to my mails..

 

Thanks - simple but hidden

Thanks for the tip. Typically Apple simple but somewhat hidden. Coming from the iPhone where it is always available, although there is less space, I could not work it out.

Thanks for your help.

John