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Royal Mail
Postage Stamps
Machin Definitives
Technical Details at a Glance

The Machin series of postage stamps is the main definitive stamp series in the United Kingdom. It is a timeless classic in use since 5 June 1967 until today and thus the longest running stamp series all over the world.
Portrait photo of Arnold Machin,
O.B.E., R.A. (* 1911, † 1999),
British sculptor,
coin and stamp designer
ex MS #2743 or PSB #DX39
First issued Machin
definitive stamp
on 5 June 1967
Photography of the
plaster cast of the
Queen's head
Pictorial label
ex PSB #DX39
First issued Machin
definitive stamp
on 15 February 1971

Printers Printing Methods Paper Types Phosphor Tagging Security Features
Perforation Gum Types Common Abbreviations Useful References Prestige Stamp Books

International Security Printers (ISP) Ltd, Wolverhampton, West Midlands, England, founded in 2004.
All printing techniques (2004 to date)
In 2004 Walsall Security Printers (WSP) acquired the French Cartor Security Printing (CSP) and established ISP to head-up these both trading companies. The old brands Walsall and Cartor were officially no longer in use. However in philatelic circles the old names are still used to distinguish the location where stamps were printed (Walsall/England or Cartor/France), eg. .... printed by ISP (Walsall) or ... printed by ISP (Cartor).
De La Rue (DLR) Security Print, Basingstoke, Hampshire, England, founded in 1813.
Photogravure (1997 to date)
Walsall Security Printers (WSP) Ltd., Walsall, West Midlands, England, established in 1966 (original company founded 1894) and appointed as supplier to Royal Mail in 1987, started printing of 14p and 19p definitive stamps for booklets in 1989.
Lithography (1989 - 1997)
Photogravure (1997 - 2004)
Since 2004 International Security Printers (ISP) Ltd
Royal Joh. Enschedé en Zonen BV, Haarlem, Noord-Holland, Netherlands, founded 1703, started printing of 8p definitive stamps in 1979.
Photogravure (1979, 1991, 1993-1996, sporadically to date)
Lithography (1997, [1st])
Cartor Security Printing (CSP), La Loupe, Eure-et-Loir, France, formed in 1974, first GB stamp printing in 2005,
Modern stamp printing by Cartor.
Since 2004 International Security Printers (ISP) Ltd
Harrison & Sons Ltd., High Wycombe, Buckinghamshire, England, founded in 1750, first British stamp printing contract in 1881, followed by a major contract in 1911 for definitives and from 1934 until the 1980s virtually every British stamp came from Harrison. In 1997 Harrison was purchased by De La Rue, but continued Machin definitives printing until late 1998.
Photogravure (1952 - 1999)
The House of Questa, London, England. Formed in 1966, first British stamp printing contract in 1980. In 1984 Waddington acquired Questa, but the stamp printing continued under the name of Questa. In 1996 Questa was sold to MDC Canada followed by the acqisition and closure of Questa in 2002 by De La Rue.
Lithography (1980 - 1997)
Photogravure (1998 - 2002)
John Waddington Security Print Ltd., Leeds, West Yorkshire, England. Established in 1922, first British stamp printing contract for 4p definitives in 1980, but own stamp production was ceased in 1986 upon acquisition by Questa.
Lithography (1980 - 1986)
More information ...

Printing Methods
photo Photogravure
A recess printing process which uses photography to produce multiple images from a master.
litho Lithography
Planographic printing process (printing from a flat surface), based on the principle that oil and water do not mix, produces a flat image. The resulting lithographed stamps are muddy and lifeless, lacking both depth and contrast. Printing firms using this method include House of Questa, Waddington, and Walsall Security Printers.
Photogravure stamp produced
by the computerized EME process
printed by De La Rue
Lithography stamp
printed by House of Questa
  Please click on one of both images to enlarge for a better view of the printing methods' difference.
Both 1st class Machin definitives come from the PSB No.DX22 »Profile on Print«.
Electro-Mechanically Engraved,
introduced in 1997 due to computerization of the printing process. The »EME« gravure process uses a computer-controlled diamond stylus to engrave the image into the printing cylinder. The precision offered by this process allows a much sharper image of the Queen's bust than was possible with the old acid-etch process.

The following five printing methods were introduced in PSB No.DX22 »Profile on Print«
EME/Photogravure by De La Rue
Lithography by House of Questa
Lithography embossed by Walsall
Intaglio engraved (recess) by Enschedé
Letterpress typographed by Harrison
Please click on images (right) to enlarge
»The Invisible Stamp«
Intaglio (recess)

Paper Types
ACP Advanced Coated Paper
under short wave ultraviolet light it is very white in appearance and gives a strong afterglow.
FCP Fluorescent Coated Paper
a chalk coated paper with an added optical brightening agent. Slightly whiter appearance than OCP.
OCP Original Coated Paper
This is a chalk coated paper with little or no optical brightening agent. It is off-white or creamy and has a dull reaction to short-wave ultraviolet light. It was gradually replaced by FCP starting in 1971.
OFNP OBA-Free Non-phosphorised Paper
OBA - Optical Brightening Agents
OFPP OBA-Free Phosphorised Paper
OBA - Optical Brightening Agents
Phosphor Coated Paper
This is a chalk coated paper incorporating a phosphor activator during manufacture. It has a dull appearance, giving a weak afterglow under short-wave ultraviolet light.
PCP1 has a dull matt appearance and a strong afterglow.
PCP2 has a very shiny appearance and a strong afterglow.

Phosphor Tagging
blue phos blue phosphorescent
(slight violet afterglow when the UV light source is removed)
Phosphor 'A' was brought into use in the mid 1980s on the ACP paper issues
(strong violet afterglow when the UV light source is removed)
colour fluor Fluoridated phosphor was brought into use in 1991 ['C'] and in 1994 ['D/D2']
'C' - this phosphor had an additive called cartax mixed with the phosphor ink
yellow/green (variations) fluorescent
'D' - blue fluorescent without afterglow
'D2' - blue/violet fluorescent with a blue or violet afterglow under long wave UV light
yellow ['C']
blue ['D']
blue ['D2']
violet ['D2']
Position and width of the phosphor bands The width of the phosphor side bands (centered down the vertical perforation over two stamps) is 9.5 mm, which results in a 4.75 mm band on one or both vertical side(s) of a single stamp. The width of a single phosphor band applied down the centre of a single stamp is 4.5 mm. The purpose of the phosphor bands is to activate the Automatic Letter Facing Machins to sort the mail into first and second class.
2-band - 9.5mm
left or right band - 4.75 mm
centre band - 4.5 mm
left band 4.75 mm
centre band 4.5 mm
right band 4.75 mm
2-band 9.5 mm
(4.75 mm each side)
  The source of the above depicted pre-decimal Machin definitives is the predecessor stamp booklet (SG# ZP1 »Stamps for Cooks«) of the PSB series.

Security Features
Starting in 2009 Royal Mail introduced new security features for the Machin definitives to improve counterfeit protection and to prevent fraudulent sale and re-use of stamps already used for postage.
RM Text pattern as iridescent overprint reading ROYALMAIL in wavy lines
SBP 1u
SBP 1i
In 2016 Royal Mail introduced a new »Security Backing Paper« for all self-adhesive Machin definitives (counter sheets, booklets). The backing paper shows an overprint under the silicone laminate. The overprint reads »ROYALMAIL« in all greyish capital letters in alternate printing of large and small size in a diagonal pattern across the backing paper.
Type 1u - lettering upright
Large size Small size
Click image to enlarge

Type 1i - lettering inverted
Large size Small size
(incorrect usage of SBP)
Click image to enlarge
SBP 2u
SBP 2i
In 2017 things became a little bit more complicated. Royal Mail had ordered a change to the security printing on the backing paper of self-adhesive stamps so that the paper could be used inverted without producing a variety. This would be achieved by printing alternate pairs of lines upside-down (Type 2u). If the paper had to be re-rolled, it would still be up the right way - but if that paper is used inverted! again a pattern variety will be produced. (Type 2i).
Type 2u - alternate lettering
Large/small size upright
Large size Small size
Large/small inverted
Large size size Small size
Click image to enlarge

Type 2i - alternate lettering
Large size upright Small size inverted
Large size inverted Small size upright
(incorrect usage of SBP)
Click image to enlarge
U [1 2 2a 3] U-shaped slits
The slits are designed to inhibit the removal of these stamps from the paper. Unfortunately this causes problems to collectors of used Machin definitives, because the slits damage the stamps when soaked.
Type 1
cuts at left and right
printed by De La Rue

Type 2
cuts at left, right,
wide at top, bottom
printed by Walsall

Type 2a
cuts at left, right,
narrow at top, bottom
printed by De La Rue

Type 3
cuts at left, right
and bottom
missing at top
(50p from PSB DX50)
printed by Walsall
  Display images

MxIL Source Code
Also in 2009 1st/2nd class NVIs appeared with a code denoting the source of the stamp. This code is "hidden" in the curvy ROYAL MAIL pattern, located above the diadem. The source code replaces the letter "A" of the word MAIL and became a standard for all new or reprinted Machin definitive issues from 2010 on.
  Source codes - type of source in brackets ()
(Business sheet)
(Booklet of Four stamps)
(Miniature sheet)
(Booklet of 2 Commemoratives
and 4 Machin NVIs)
(Booklet of Six stamps)
(Prestige stamp book)
(Rolls [coils])
(Booklet of Twelve stamps)
MAIL (no code)
(Counter sheet)
  Display images
Source code is "hidden" in the word ROYAL instead of the word MAIL, only 1st/2nd Large NVIs issued in 2009.
(Booklet of Four stamps)
(Business sheet)
ROYAL (no code)
(Counter sheet)
  Display images
The text pattern overprint of the Machin NVIs issued on 6 February 2012 read
The 1st class NVIs have the letter "O" of the word DIAMOND (just below the back of the crown) replaced by the corresponding source code.
The 1st class Large NVIs have the letter "E" of the word JUBILEE replaced by the corresponding source code.
(Business sheet)
S T C M P, no code
(other possible source codes)
(Booklet of Four stamps)
B, no code
(other possible source codes)
  Display images
MAyy | MyyL Year Code
In 2009 all Machin NVIs and the self-adhesive 50p stamp from PSB SG# DX50 were issued with a code denoting the production year of the stamp. This code is "hidden" in the text pattern overprint. The last two digits of the year of printing replaces the letters "IL" or "AI" of the word MAIL/MAIL and became a standard for all new or reprinted Machin definitive issues from 2011 on, apart from very few exceptions (e.g. 2012 Diamon Jubilee NVIs do not have a year code).
  Display images

Perforation Measurement
(The gauge of a perforation is the number of holes in a length of 2 cm)
perf 15 Standard perforation is 15 x 14 (actually 14¾ x 14¼)
15 teeth along top edge
perf 14 Perforation 14 x 14 (actually 13¾ x 14¼) by Walsall,
or (actually 13½ x 14¼) by Questa and Waddington

14 teeth along top edge
  The vast majority of Machins are perforated 15x14 but some of them also exist with both perforation varieties, mainly regionals (see reference).
[perf 13] Perforation 12¾ x 13 was caused by the use of an
incorrect perforation comb by Walsall, on stamps

NVI 1st bright orange-red, SG# 1516c ex booklet
SG# HB3a, Okt 1990

13 teeth along top edge
Please click
el perf 15
el perf 14
Brought into use on 6 April 1993 a three hole ellipse on each vertical edge of the stamp was added as a security feature to prevent re-use and deter forgery.
Elliptical perforation 15 x 14 (actually 14¾ x 14¼)
Elliptical perforation 14 x 14 (actually 13¾ x 14¼ or 13½ x 14¼)
Since then, two types of elliptical holes have been identified:
narrow at top and bottom, with rounded sides (eR[ugby ball shape]), De La Rue (and others) printings
wide at top and bottom, with almost straight sides (eS[ausage shape]), House of Questa Printings
Identifying these two types of elliptical perforations on single stamps is rather difficult, pairs or blocks make it easier.
Elliptical perforation
at left: Type eRRugby ball« shape)
at right: Type eSSausage« shape)
SG# U3012b (5p) // U3017 (50p)
19 Sep 2013 // ex PSB »Merchant Navy« SG# DY8
misplaced elliptical perforations at top
of sides of stamp - printed by Enschedé
SG# W72 //23 July 1996 // 20p // bt green // Wales
Elliptical perforation - Type eS
printed by House of Questa
SG# Y1722 // 27 March 2007 // 48p // Rhododendron
Elliptical perforation - Type eR
printed by De La Rue
(el) dc (Elliptical) die-cut 14 x 15 or 14½ x 14, self-adhesive stamps,
in PSBs the first self-adhesive stamps appeared in #DX22 »Profile on Print«

Gum Types
wag water activated gum GA Gum Arabic, white shiny, until the late 1960s
PVA Polyvinyl Alcohol, matt shiny
since 1993 yellowish or bluish-green
or white matt-shiny
PVAD or Dex Polyvinyl Alcohol + Dextrine additive
Dextrine Additive (bluish-green gum)
SA Self-Adhesive gum (Acrylic) PVAI Polyvinyl Alcohol Layflat
(first tested on the 19p/25P values issued in 1995)

Common Abbreviations
SG# Stanley Gibbons catalogue numbers referring to
Great Britain Concise Stamp Catalogue 2014
SG »Prestige Stamp Book« numbers
PSB Prestige Stamp Book NVI Non Value Indicators, first appearance of non-
denominated Machins in 1989
(1st, 2nd, E[urope, 1999], Worldwide, etc.)
MD Machin Definitives MRD Machin Regional Definitives
CD Country Definitives SS Special (commemorative) Stamps

Useful References
Royal Mail Stamps Stanley Gibbons Catalogues
»Deegam« () Machin Handbook Britain's Marvelous Machins
Machin database created by Robin Harris Machin Colours
Norvic Philatelics Norvic Philatelics Blog
Collect GB Stamps  
We were saddened to hear of the passing of Douglas Myall [»Deegam«] on 30 January 2019.
He was the leading authority of Great Britain Machins.


// Elmar R. Göller // All rights reserved // Contact // Publishing Information