Great Britain Traffic Light Gutter Pairs

I have recently discovered an interesting new facet to collecting Great Britain .... in addition to prestige books and presentation packs that I've discovered in the last year or so I've come across something called traffic light gutter pairs.
Is there a better reference source than Stanley Gibbons Great Britain concise annual catalogue .?
And is anyone aware of a source of album Pages for these ?
Maybe even a specialist group or study circle ?

Any and all help and information is greatly appreciated thanks

Referred to, as "Marginal Markings"
Go googling,
MM 101
http://www.earsathome.com/markis.html
http://goscf.com/t/10406#93224 br /

Traffic lights are colour registration dots. They come in many shapes and sizes. Harrison used dots, Questa used Qs and I think it was Waddington that used squares. Each dot – or light – corresponds to a colour used to print the stamp. Harrison boxed the colour dots, giving rise to something that looked like traffic lights.

Stamps, normally, have been printed in sheets that are much bigger than the sheets counter clerks have in their books. The panes are separated by gutters and cut through those margins before distribution. Counter sheets of commemorative stamps often were distributed as double pane sheets.

From the Royal Silver Wedding set of 1972 until the 1979 Christmas set, Harrison placed the traffic lights in the gutter margin of the counter sheets, thus giving rise to the traffic light gutter pairs. They also exist with the large format Machin high values.

There really is little to add to the Concise listing. If you find a certain stamp is missing a colour or has a colour shift – that is rarely catalogued – the corresponding traffic light dot will be missing or shifted. Maybe the SG Great Britain Specialised Catalogue, vol. 5, for decimal commemorative stamps has more information.

This picture shows the traffic light Gutter pair Jim1952 refers to. Harrison printed the traffic light in the sheet margin. Harrison's Jumelle press printed double pane sheets separated by a central gutter. For the period I mentioned above, Harrison printed the traffic light in the central guyyer margin, giving rise to "Traffic Light Gutter Pairs." Without the traffic light, it is just a "Gutter Pair."

In some issues, the traffic light extends beyond the gutter of the second column.

Another way of boosting philatelic sales! I seem to remember that one country (probably commonwealth) used to put traffic lights on every gutter pair. This is as bad as Canada's habit of putting an inscription in all four corners of a sheet and promoting matched sets of blocks.

Nope, it had nothing to do with philatelic sales. This was a new press that Harrison used. Its origin was purely operational.