Arnold Machin's approach to the new portrait was preferred by the Stamp Advisory Committee. In February 1966 he began work in earnest using photographs of a plaster mould which had been created, but then rejected, for coins.

From this he developed an image of The Queen wearing a tiara, but adapted the design so it was facing left (on coins she faced right).

The process of creating a plaster relief begins with a flat plaster 'bat' or base. On this a clay model is built up and moulded. The clay work is facing in the correct direction. To make the plaster mould a fence or frame is placed around the clay. Then the (plaster bat) background is soaped to form a release. Casting plaster is then poured over the clay. This sets quickly, giving out heat as it does.

Once set, the two sections part naturally. Often the clay is destroyed at this stage as some clay sticks to the bat, some to the cast. This operation created the mould (wrong facing). Machin could then clean any remaining clay out of the mould using the stickiness of further lumps of clay.

To create the relief sculpture the plaster mould is painted with soap and another plaster is cast. This gives the first impression of the relief in plaster (correct facing). Machin could remove plaster at this stage with various tools i.e. he could cut back. However, if he wanted to add something then another mould would have to be taken.

When Machin had reached a certain point the relief sculpture was photographed. This image is now known as Machin's 'Coinage Head'.

The photograph was then used by the printers in a variety of frames. These showed regional symbols, possibly based on a sketch by Machin. The printers produced a range of stamp essays in April and May 1966. The head was generally regarded as unrecognisable as The Queen.

Between May and August 1966 Machin simplified his 'Coinage Head' and the surrounding design. The simplified version showed just the head and stamp value on a solid colour background. The value was fashioned in another plaster cast.

Essays of the simplified design, still showing The Queen wearing a tiara, were produced in October. These were compared with others based on a photograph by John Hedgecoe where The Queen wore the diadem.

Illustrations

Original plaster mould for the coinage head

Coin photo worked on by Machin

Plaster case based on Coinage Head

Essay of simplified Coinage Head