It was quite an expensive machine considering the size of it and at the time it was being sold. My machine has a sticker on the painted red pull cord housing with a serial number and the address it was manufactured at. Turbair Ltd, Britannica Works, Waltham Abbey, Essex, England. I recall reading last week that a machine this size could treat an area of commercial glasshouse/polythene tunnel of upto 3000 square metres which is almost one acre (one acre is 4000 square metres in area). It is quite a large area considering how small this little turbair machine is. I have seen modern commercial fogging machines used for pest and disease control in glasshouses. Some of them are much bigger with much larger fans that are pulled along like a trailer.
I don't think people were aware of the dangers of spraying without proper PPE years ago, particularly when you consider what was being sprayed 30-40 years ago. Some of the insecticides and fungicides being used were really toxic and hazardous to health !
I will take a look at the forestry commission article.
Mark