Sub Report Padding

I have embedded a sub report into my main report.

I am putting my sub report flush left and top of the Detail band, but when I generate the report, it is positioned down and to the right. It looks like there is top and left padding of the sub report but I can't find settings for this anywhere.

Does anyone know how to display a sub report against the left and top of the page without the 'padding'?

Thanks in advance.

Jason