When I started collecting in 1986 which focus on Straits Settlements and Malaya banknotes, QEII portrait appear in the 1953 issue of the Malaya and British Borneo banknotes. At that time, it was quite cheap especially for the smallest denomination of $1 ( The first banknote listed on this thread ). I bought them in stacks ( 50 pieces in running and one stack was 93 pieces in running number ) and later sold them away in one of the coin convention to USA and other foreign dealers. I kept some and over the years, sold them away bit by bit. The Queen Portrait was one of the most beautiful among all her other portraits. The other denomination are $5, $10, $50, $100, $1000, $10,000. Those $1000 and $10,000 only exists in specimen, proof pieces which once in a while appear in international auction all over the world.
The $100 is the most difficult to find in nice condition even 20 years ago. There are quite a number $50 around but they are most in VF to AEF condition. If you buy them today, they may be pressed, washed and graded AUNC. This apply to even $5, $10 as well. I once help a friend to sell off a set of these notes. He paid high for them as he did not know that they were washed and pressed. When I examined the notes, they were indeed washed and pressed. I do not sell washed and pressed notes. If I do sell them, I will state them clearly. They look good in their sealed plastic sheet. But when they are opened and take out from the plastic sheet, all truth were revealed. Some even started to curl up slowly and show signs of heavy water-pressed notes. They are also very thin. Be exceptionally careful when purchasing them. If you think that it is a good buy with such nice looking note and such good price, you may be taken for a ride.
Here is a popular special number note which I acquired 3 years ago. It has been pressed ( I do not mind ). I go for the special number solely for my collection since I won't be able to find another one with such suitable number for my collection.