I had a brainwave and looked on eBay for sellers showing the old packaging. I found one showing the back of the packet.
View attachment 332830
Comparing the two, values as %
Nitrogen old 0.28, new 0.8
Phosphate old 0.11, new 0.17
Potash old 0.28, new 0.16
Calcium old 14.9, new 23.3
Magnesium old 0.06, new 0.29
Sulfur old 12.2, new 16.15
Boron old 0.029, new 0.003
Chlorine old 0.55, new not listed
Cobalt old 0.001, new 0.002
Copper old 0.001, new 0.006
Iron old 2.2, new 3.07
Manganese old 0.23, new 0.16
Molybdenum old 0.0009, new 0.0005
Sodium old 0.14, new not listed
Zinc old 0.0024, new 0.003
'New improved' contains more nitrogen, phosphate, calcium, magnesium, sulfur, cobalt, copper, iron, zinc.
'New improved' contains less potash, boron, manganese, molybdenum.
'New improved' has dropped sodium, chlorine.