After our previous posts about marginal markings, Roy asked me about perhaps the most well-known ones, the circular registration marks. These marks are reminiscent of traffic lights and are generally called that.
In the Machin series, traffic lights only appear on the large-size photogravure high values. They were located in the gutter between the stamp panes. (The stamps were printed in sheets containing the two panes with the gutter between them. The panes were generally separated before being distributed to post offices, but complete sheets were also made available, allowing gutter pairs to be saved. Does anyone remember how many stamps were in each pane of these values?)
This format of two stamps separated by the gutter is called a "traffic light gutter pair."
These photogravure Machins were issued in 1977 to replace the recess-printed high values that were issued in 1970. (The 10p from that group is shown here.)
The conversion to photogravure was presumably done to save money, since gravure stamps are less expensive to print than engraved ones. The Post Office compensated a bit by making the stamps larger and printing them in two colors. Jeffery Matthews designed the stamps using, of course, the Machin portrait.
The initial set of values, £1 olive and greenish yellow, £2 purple brown and pale green, and £5 royal blue and pale pink were issued on February 2, 1977. (I'm using Douglas Myall's color names, other catalogs will differ.)
These stamps didn't pay any specific postal rate. They were just used for parcels and costly services such as insurance.
Six years later, on August 3, 1983, a £1.30 blue-green and buff stamp was issued in the same format. This stamp paid the first weight step (up to 1 kilogram) for parcels mailed within the U.K. As the parcel rate increased, new stamps were issued: £1.33 blue-black and mauve on August 28, 1984, £1.41 blue-green and buff on September 17, 1985, £1.50 blue-black and lilac on September 2, 1986 and finally £1.60 blue-black and buff on August 15, 1987. Notice the alternating color scheme for these stamps.
All of these high-value Machins were discontinued in 1988 when the decimal castles appeared to replace them. Never again were stamps issued to pay the basic parcel rate.
These stamps can be collected as singles, gutter pairs (with blank gutter) and traffic light gutter pairs. The normal cylinder blocks also exist. The items that these stamps were usually used on, parcels and such, did not pass through the automated letter sorting machines. Therefore, these stamps do not have phosphor bands and are printed on regular, non-phosphorized paper. There are some varieties of color shade and perforation type for those who want a specialized collection of these stamps.
The gutter pairs are individually listed in the Machin Collectors Club Catalogue. The set of eight gutter pairs is listed in the Stanley Gibbons Concise, but not individual pairs. And the Stanley Gibbons Specialized doesn't mention them at all.
As an aside, even though these stamps are simply larger versions of the standard Machin design, I (and some others) don't find them as attractive as the standard Machins. If you disagree, let us know in the comments.