|I have said above that GPT are consistent in their choice of controls and so they are for mainstream cards but this does not extend to the private cards of some countries. For Singapore and Malaysia, for example, the normal three letter country designation is replaced by letters corresponding to the advertiser or sponsor. The initial letter is retained but the second and third letter generally reflect the sponsors initials. Normal Singapore cards have the control letters SIG as mentioned above but the many cards that have been sponsored by Fuji have SFU and those by NEC have SNE controls. Similarly Malaysia Uniphone normally has MSA but the advertising cards for Petronas have MPE controls. The GPT cards for Mercury, UK, however, had MER controls regardless of whether they are public or private cards.
New Zealand too has a somewhat idiosyncratic control numbering system. The early cards were perfectly well behaved with NZL controls starting with 1NZL for the trial cards in the usual way 2NZL for the First Issue cards, 3NZL, 4NZL and 5NZL for the Satellites and so on. The 1990 Christmas set however was of five cards with controls 6NZAB, 6NZBB, 6NZCB, 6NZLC and 6NZLD, presumably to reflect that fact that the first three were all of the same value, and this practice continued on later sets over the next year. The 1991 Christmas set saw yet another change of system with controls 101B, 102B, 101C and 101D where again the first two are of the same value The Antarctic set issued in February, 1992 reverted to the 1991 system while the Summer Sports set in March, 1992, had 111B, 112B, 111C, 111D and 111E, the Winter Sports set in June, 1992 had 113B, 114B, 112C and 112D and the Hedgehog set of August, 1992, had 121B, 122B, 121C and 121D. While one can see some sort of a pattern here, the logic is not self-evident.
There has in fact been a trend towards eccentric control numbering systems with encoding, and hence numbering, taking place in the country of use rather than that of manufacture. Thus Saudi Arabia, in compliance with Saudi law, now encodes its own GPT cards and applies the control numbers, and Sapura in Malaysia does both its own Uniphone cards and those of Vietnam which are provided through Sapura.
ll of the above comments relate, of course, to cards as they are produced by GPT. The situation can become confused when telcos take to overprinting excess cards of one design with a new design. Mercury, UK, which has now ceased to issue cards, acquired the technology to take the design surface off cards leaving a matt black surface for reprinting. This had several interesting effects. The numbers of cards of the types so processed were reduced from the numbers originally printed and listed in the catalogues. Controls previously associated with certain cards appeared on new cards and new cards appeared with a wide variety of controls on any one design. One card featuring an Airedale dog, of which only 1000 were printed, occurs with no less than six different control prefixes and a single card with a deep notch! New Zealand also took to overprinting older cards but without taking off the old design first. This not only gives rise to anomalous controls but also to cards which have to be handled with great care if the new design is not to be damaged!
Finally, I cannot stress too much that controls on GPT cards are taken very seriously in most countries employing those cards. Most collectors are not content with one card of each design but want one of each printing as indicated by the initial number of the control prefix. The differences in value between cards of the same design but different control prefixes can be significant. There were 5000 of the Mercury First Issue £2 cards with controls 1MERB.... 2MERB... and 4MERB... and these were at one time valued at £125, £100 and L80 respectively. For Singapore the $50 gold card catalogues at $400 unused for control prefix 5SIG... and at $85 for 9SIG while the Queen's Visit set all show 2SIG... and 3SIG... controls, the former being about three times the value of the latter in each case.
Text by Steve Hiscocks.