Madeira Ceres Issue 1928 Or 1929?

This set of 21 stamps printed by Perkins, Bacon is listed as being obligatory on certain days of the year.

In Stanley Gibbons it is listed as being issued in 1929 and doesn't give any dates.

In Scott (2009), on various wiki websites and in a Linns online article it is listed as being issued on 1st May 1928 and the obligatory dates are given as 1 May, 5 June, 1 July, and 31 December 1928, and 1 January, 31 January, 1 May, and 5 June 1929.

In a RPSL article reviewing the engraving books of Perkins, Bacon by E.D.Bacon, it says that the die was engraved on 13th December 1928.

This has always puzzled me so on a recent visit to the RPSL I checked the archives. The engraving date is indeed 13th December 1928 and furthermore the printing of the stamps didn't start until 28th December 1928.

The stamps couldn't therefore have been issued on 1st May 1928 nor could they be used on the dates quoted in 1928.

Does anyone have any further information that could shed light on this discrepency?

In this link the set is incicated year: 1929....,?
https://www.isabelraposo-filateliac...opia-madeira

My 1982 edition of the Eladios de Santos catalog shows the set as being issued in 1929.

Thanks. Goes to show how incorrect details gets copied and eventually becomes fact. Fake news

Good evening,

After several difficulties with the emission of the stamps... the law said these stamps were obligatory on 1 May, 5 June, 1 July and 31 December 1928 and also 1 and 31 January, 1 May and 5 June 1929. (1)

However... maybe they were used/obligatory only in 31 January, 1 May and 5 June 1929 (2)... in spite of they could be used on the other days fom 1 May to 5 June 1929. (3)

Some stamp catalogs say they were issued on 1 May 1928 and others 1929 however they have no more details about these dates.

Synthesis (until now)

It will be necessary to do more researches...

SOURCES AND BIBLIOGRAPHY (Portuguese language)
(1) - Decreto nº14:700 of 3 December 1927 (Decree)
(2) - According to the known stamps/cachets we use to see "here and there" and also to the following book:
SARMENTO, Alberto Artur (1933). Moedas, Sêlos, Papel Selado e Medalhas na Madeira. Funchal: Typ. Camões.
(3) - In accordance with the art. 1, § unique of the Decree nº14:700 above quoted.