Outer sill filler panel

[ps4330@okc01.rb.jccbi.gov (Peter Schauss x 2014)]

Among the parts which Moss lists for repairing the sills on the MGB is
something called an "outer sill filler panel"  (I am working from memory
here so the wording may not be exactly that.)  It is a three sided piece
which appears to match, roughly, the profile of the outer sill.  
Can someone tell me where this is supposed to go?

Thanks,
Peter Schauss
ps4330@okc01.rb.jccbi.gov
pschauss@aol.com
1963 Austin-Healey 3000 Mk II
1980 MGB