It was 12 years before Enschede were awarded another contract (1991) when they produced the 18p value. Then in 1993 all numerical Machin definitves in sheets were transfered and printed in Holland.
With this change over the Enschede imprint replaced that of Harrison & Sons in the margins of the sheets, this can be found apposite row 20. No phosphor cylinder numbers were used but the ink cylinder was, this can be seen in row 18. As with Harrison printings the sheets of 400 were printed and seperated into two, so both dot and no dot sheets exist.
Several transitions followed throughout a two year period, the contract ending in 1995. These transitions were enough to change the design and produce new collectable varieties.
Over the months to follow, different coloured phosphors and varnishes were applied to eradicate problems. Yellow phosphor (in different stages of thickness and colour) 4mm varnish under the phosphor ink, followed by a 2mm varnish, a change to from yellow to blue phosphor and the use of different coloured gums was also to follow. Blue tinted , white and cream gums are known. This gave the specialist collector an array of individual different stamps to aquire and catalogue.
Another difference was also noted, from 2 extension holes in the margins, which reverted to just one.
When collecting mint copies I always recommend collecting these in Cylinder block form, but it is not often one sees them for sale.
Well If you are interested I have news for you, as I recently acquired a small collection in cylinder block form which are surpus to requirements. Rather than sell these through my website I have listed some of them on eBay ( more to follow). Take a look you may be pleasantly surprised at the starting prices. I am also offereing discount postage (25p UK, Europe and(worldwide) . Winners will only pay an extra 25p for each multiple win.
If you fancey a dabble here is the URL.