A few posters seem to be asking, "What if the Glazers do not write off their portion of the PIK notes?"
Well, if we take GCHQ's assumption that the notes would have to be paid off evenly, that is, any payment towards them would have to be spread across all the notes regardless of the identity of the holder, then you'll find that the net effect would be exactly the same as if the Glazers did write off their portion of the PIK's.
In explanation of this, look above at the 'Scenario B' spreadsheet. This shows how soon the PIK's could possibly be eradicated if the Glazers wrote off their portion. Look at the 'Total PIK' level for year 2011; after the £95m payment is made and the interest added for 2010, the total of outstanding PIK debt in 2011 is £91m.
Now, consider what would happen in the same situation but instead with the Glazers' portion of the PIK notes still in place.
The Total PIK debt year 2010 would be £200m, and once interest is added at 16.5% this would increase to £233m, divided 20% - £46.6, and 80% - £186.4 between the Glazers and third party holders.
The £95m payment would then similarly have to be divided, 20% - £19m, and 80% - £76m, which would reduce the total debt to a split of 20% - £27.6m, and 80% - £110.4m between the Glazers and third parties.
Now, the Glazers have just paid themselves £19m for their 20% holding of the PIK notes, so this extra cash can be paid back in.
Split it 20% - £3.8m, and 80% - £15.2m and the new PIK totals are; 20% - £23.8m, and 80% - £95.2m.
Again, the Glazers just paid themselves £3.8m, which can again be paid back on the PIK's. You get the gist;
Split 20% - £0.8m, and 80% - £3m the new totals would be 20% - £23m, and 80% - £92.2m.
This process can continue indefinitely until you're calculating just pence, but if you stop there for the sake of sanity, look at the total PIK debt for the remainig 80%; £92.2m; remarkably close to Scenario B's £91m in the same year; i can assure you that the £1.2m difference comes only from rounding the figures up or down through various stages of each calculation; the net effect to the PIK's would be exactly the same regardless of whether or not the Glazers write off their portion.
So by buying the 20% in 2008 the Glazers have effectively already written off that portion of the debt, because an IOU to oneself is absolutely worthless; either way, whether they write off the PIK's now or continue to hold them for tax purposes or whatever, the net effect to the remaining 80% is equal.
Edit.
This is purely just a mathematical concept, perhaps anders, GCHQ or someone else could comment and expand upon its practical application?