I have just added an article by Margaret Jokelson that first appeared in the 1957 PCA to Scotland's Glass.LINK
Can anyone identify the assistant.
A bonus is the images which where taken by P K McClaren who with his brother photographed at both factories extensively and won press awards. Sadly their negatives were destroyed following their deaths and few images remain.
Thanks to KevH who alerted me to this article and prepared the text for use.