E-mail Signature Alignment

I have had a nice HTML email signature created, I have added it via the HTML code to my desktop email clients and I've been trying to add it to the iPhone.

So I understand and believe that I need to copy and paste the actual sig in to the signature box on the mail settings on the phone. I have done this however when I send a message the signature is centred in the middle of the message rather than appearing on the left.

It looks great sending iphone to iphone, but once I send from iphone to desktop (thunderbird and gmail) the signature appears centered rather than aligned left.

I have attached an image, I want it to appear under the "Hello"

Does anyone have any ideas?

Thanks

Nick