While filling the repayment form in there's a section where your requested to state the serial number(s) of the enclosed Prize Bonds.
A prize bond has a from and to on it as "bond numbers".
The spaces in the form seem to be for single numbers (thus if I was to use this which one do I use, the from or to or both?).
The back on the prize bond on the right corner has a seven digit number (not labelled). Is this the "serial number"?