We would expect that on a modern series issued in an era when there were very many active collectors all replacement note dates would be recorded and saved in UNC grade. This however, proved not to be the case with C Series replacement £20 notes. Despite our best efforts, some of the dates were never secured in UNC.
There were a lot of dates for the £20. At the start of the issue in 1992 collectors kept an eye out for replacements of the new series as they came out. A couple of days after the notes were issued I got three replacement notes in the first batch, two 21.09.92 notes, and a 10.09.92. The earlier date was a surprise! Everyone started looking for the notes, but very few turned up. The printage of these was very low.
14.01.94 BBB is very rare, with a small printage, likely the lowest of any replacement.
They were out and gone before anyone spotted them!
At the end of the series just before the Euro was introduced, it again became difficult to obtain UNC replacement notes. Of the four PPP dates only one, 16.02.99, has been seen in UNC. Very few examples of the other dates have been seen in any grade, despite a large overall printage.
The following dates for B Series replacement notes have never been recorded in UNC grade.
All of them are rarely seen as replacement notes.
10.09.92 exists only as a replacement and is a very rare date.