Thanks Nigelc. I managed to source the list of issuances and variations from this site
http://www.thingspostal.org.uk/east...3dues-m.html It is quite detailed. Also the stamps that I had fitted neatly into their listings. Only problem was there was no SG ref hence I asked for assistance. The SG dates and stamp variations tally very closely with just one date out a bit. However according to the lists on the site above and my own collection, there are only 5 stamps in the 20/3/73 (they say 20/2/73) p14x15 glazed ordinary paper. The SG numbering SGD23-28 implies there are 6. My stamps are 5c, 10c, 20c, 40c, 1s. Am I missing one or was there a later addition to the set? Many Thanks.