Fake British Consular Stamps - Printed for the "Haganah"

A sheet of fake British consular stamps printed for the "Haganah" in order to forge certificates. [Merhavia, second half of 1940s].
Stamps with the writing "Consular Service" and a photo of the King of England, printed to be used for fake Aliya certificates, as part of "Aliya Daled".
"Aliya Daled" is the name of a system to let illegal immigrants enter Palestine with fake certificates, introduced in 1947. The certificates were faked using fake British consular stamps and ink-stamps. The initiator of this idea, who also materialized it, was Shlomo Zimermann. Zimermann said that they succeeded in forging various British visas - tourists visas, Aliya certificates, visas for returning citizens - and to accord passports by exchanging photos. In order to verify that there are no problems upon arrival, Zimermann and his colleagues recruited a Jewish Passport Control clerk in Haifa port, who - for payment - took the risk and made all the holders of forged documents - pass. During the "Aliya Daled" operation thousands of immigrants from various places arrived. All of this operation was done through Haifa Port and by Zimermann and the "Institute for Aliya Bet" in Haifa
Enclosed is a copy of a letter from the commander of "Aliya Bet Institute", Shaul Avigur, to Yehudah Slutzky, historian and author, who wrote, among others, a book about the history of the "Haganah". In this letter Avigur states that "the stamps were printed in Merhavia printing press, the perforation was done in "Ot" printing press in Haifa and the clichés in Zincography". The graphic designer was, most probably, Nathan Shelker.
21 stamps per sheet. Good condition.