First of all, I must congratulate Glen on generating so much interest in this particular £5 Orange. It was very effective use of Polling.
The stamp is described in more detail as an erased specimen in the forgeries section of both "The £5 Orange" book and my Large Gold display.
I will try to address some of the issues raised in the earlier posts to this board. Here is the certificate:
It clearly states 'SG133 is genuine' without qualification.
Below is the reverse side in which there is very little trace of the original Specimen overprint, but there is no doubt that it is blued paper - as indeed most type 9 Specimens are.
Three versions of this style of the Threadneedle Street registered oval have been used with the £5 Orange. They have code letters A, B and C. During research for the £5 Orange book, I trawled through the Date Stamp Impressions books at the British Postal Museum and Archive in London (BPMA).
I only found two of the A,B,C code letters for Threadneedle St, both struck well after 1883. As the code letter is unclear in the cancel on this particular stamp, it could be the one missing from the BPMA records, although it would be somewhat anachronistic.
The letters THREAD appear smaller than those in NEEDLE which is suspicious, but with at least one known missing strike in the Impression books, it could not be totally ruled out.
If it is forged, it is not a known Madame Joseph. If real, then it looks like fraudulent use - of which other examples are shown in the book.
There is a registered oval recorded for Threadneedle St which is dated well before 1883 (1871 from memory) but its style is very different.
In summary, the basic stamp is genuine on blued paper. The colour is fine, the perfs are fine, the watermark is correct, there are no creases, tears or repairs. It appears to be a very fine example of SG133 - so good that the RPS gave it a clean certificate.
The only problem is that the cancel is actually hiding an erased specimen.