My 2001 Specialised Vol. 1 lists the stamps from plate 1 as SG J97(1)* or SG 112 (red-brown) and J97(3)* or SG 114 (deep red-brown). The abnormal that was printed from plate 2 but never issued is listed as SG J98* or SG 113. It does look like stamps from plates 1 and 2 were listed, and then a deep colour variety of the stamp from plate 1.
I took these screenshots of the available SG 112 and SG 114 stamps offered on Stanley Gibbons' website, today. The descriptions are for the plate 1 stamps and plate number 1 shows in all images, coinciding with the 2001 listing.
* The J-numbers are those assigned for the specialised listing.


Your stamp, clearly, was printed from plate 2, being the 'abnormal.' A great stamp to have in your collection. This is listed as SG 113.
Now, the specialised also lists a pale red-brown stamp from plate 1, J97(1)*. Interestingly, on the Stanley Gibbons website, this also is on offer and identified as SG 113.

It does raise the question if the Concise listing has been changed after 2001 and assigned the 'abnormal' a new number, like 112a, or no longer list it in the Concise. It would explain why it appears under so many numbers.Edit: The 'abnormal' J 98 or SG 113 is listed as having a pale red-brown colour. That, probably, is the reason the plate 1 stamp in that colour, also, is listed as SG 113. If I remember correctly, Concise does not assign separate numbers to plates.
I have been waiting quite some time for part 2 of the new Specialised Vol. 1. It should have appeared in 2021, but there is no trace of it yet. This would list the surface printed stamps.