GB Machin- Sg Help Needed!

I have acquired a stockbook pretty well stocked with elliptical perf. Machins.
The P.O. had them nicely sorted by value and SG numbers-but many of the numbers don`t match with my 2022 catalogue. There was a biggish re-numbering some years back (?)-is there a check list somewhere to marry up the old and the new?
By way of example- 6p olive was Y1748, now1766 it seems, and this is also tagged as UG22-now what is that ref?
Apart from photo/litho sorting (pretty straightforward to sort), he also has them sub sorted by printer (Harrison/Enshede etc.). How do you that with used stamps from unknown origin.- so I need some guidance on this please and maybe some more instructive reading.
Your help would be much appreciated-thanks in advance

UG is an SG Specialised Catalogue number. Y is a basic, provisional number you will find in the SG Concise Catalogue.

Often, the phosphor bars are a good way to identify whether a stamp was printed by Harrison or Enschedé. For your 6p, the fluorescent agent in the phosphor bar always was blue on the Harrison stamps. Yellow fluor stamps are Enschedé. The Enschedé stamps with 'blue' phosphor bars has another type of blue fluor added. Also, details of the head are different.

Well I`m digging in to my many Machins and trying to get to grips with the details and starting at 1p, which seems sensible.
I`ve found this unlikely `head` with a double chin appearance which also effects the nose ,back of hair and the diagonal back of the crown, The double chin is quite striking and appears also on a 2p green from the same Questa booklet.

I am hopeful that now this series is reaching an end, cataloguers will be able to put out a defintive listing (no pun intended), covering verious levels of detail,safe in the knoweldge that there won't be some new set out next year which will interrupt the sequencing.

That is called the Deegam Handbook and has been around for a few decades.

Deegam has to be regularly updated - that's the problem. Until now you could never say you had the full catalogue, just the latest instalment. I have never owned Deegam but my impression is it's vastly detailed, much more than most will need (or understand).

As long as a country issues stamp, new issues will be added tothe catalogue.

Deegam does it exactly in the way




It is very detailed, but lists at three levels. So, you can collect at any of those levels. The first comes close to the SG Specialised level.